APPEAL COURT, HIGH COURT OF JUSTICIARY
Lord Justice General
Lord Nimmo Smith
Appeal No: C353/99
OPINION OF THE COURT
delivered by THE LORD JUSTICE GENERAL
NOTE OF APPEAL AGAINST CONVICTION
KIM LOUISE SCARSBROOK or GALBRAITH
HER MAJESTY'S ADVOCATE
Appellant: Scott, McColl; McCourts
Respondent: Solicitor General (Davidson, Q.C.); Crown Agent
21 June 2001 (Opinion issued 18 July 2001)
This appeal by Kim Louise Scarsbrook or Galbraith against her conviction of murdering her husband was first heard by a court of three judges. On 7 June, for the reasons outlined in the opinion delivered by the Lord Justice General, that court decided to remit the appeal for a hearing before a larger court so that we could consider various issues relating to the trial judge's directions on diminished responsibility. As the Lord Justice General explained, there were in fact three grounds of appeal but it was decided that the larger court should begin by considering the appellant's appeal on the third ground which raised these particular issues. In the event, for the reasons which we now give, we decided on 21 June to allow the appeal on this third ground and, in terms of Section 118(1)(c) of the Criminal Procedure (Scotland) Act 1995, we set aside the verdict, quashed the conviction and, since significant issues of credibility arose, granted the Crown authority to bring a new prosecution in accordance with Section 119. For that reason it was unnecessary for us to consider either of the other two grounds of appeal and Miss Scott, who appeared for the appellant, did not indeed advance them before the larger court.
 Since we were satisfied that there had been a misdirection and the Crown did not suggest that it was other than material or that there had been no miscarriage of justice, we give no more than the brief outline of the evidence which is needed to provide a setting for our discussion.
 The Evidence and Issues at the Trial
For some time before January 1999 the appellant and the deceased had lived together at Furnace near Inveraray - in quite a rural area. The deceased was a policeman and acted also as a part-time gamekeeper. In connexion with his game-keeping the deceased held a firearms certificate and he sometimes kept firearms at home. At the trial the appellant admitted that, in the early hours of the morning of 14 January 1999, she had shot the deceased using a rifle which he kept in the house. Her contention was, however, that her responsibility for her actions had been diminished at the time when she killed him. She should therefore be convicted of culpable homicide only.
 In support of that plea the appellant gave evidence to the effect that the deceased had abused her in a number of ways over a period of years. In particular he had subjected her to violent sexual abuse of various kinds. He had threatened to kill her if she did not submit. She had feared that he would indeed kill her and she felt under threat both physically and mentally. He had had pornographic video recordings in the house. She had been ashamed of the situation and had felt unable to tell anyone about what the deceased had done to her. She had considered that, if she had left the deceased, he would have followed and found her. She just could not take any more. She had killed the deceased because she could not think of any other way in which to bring her tribulations to an end. In paragraphs 7 and 8 below we refer to some of the evidence which the defence led in support of the appellant's contention.
 The Crown position was that the appellant's account of being subjected to abuse by the deceased was untrue. They led evidence which was designed to show that the deceased had not been the kind of man depicted by the appellant. In particular the deceased's first wife said that her marriage to him had been perfectly happy until he appeared to lose interest in it. There had been no threats, abuse or unusual sexual practices and no physical harm. The truth of the appellant's account of abuse, which formed the central plank of her defence of diminished responsibility, was therefore sharply in issue at the trial. Moreover, the jury would have had to accept her account as substantially true before they could have returned a verdict of culpable homicide. That was, quintessentially, a jury question.
 It may indeed be - we cannot tell - that the majority of the jury convicted the appellant of murder because they rejected her account of the supposed history of abuse. An important element in the Crown case was the evidence which showed that the appellant's killing of her husband was carefully prepared. In particular, she carried out certain steps, both before and after the killing, which were designed to suggest that the crime had been committed by two intruders in the course of an attack in which she had been raped and her handbag had been rifled. Indeed, five or ten minutes after killing the deceased, the appellant made a long 999 call to the police in which she gave an account of the intruders killing the deceased and of one of them raping her. Only in an interview with the police some hours later did the appellant admit killing the deceased.
 In support of the appellant's plea of diminished responsibility, the defence led the evidence of two psychologists. The first was a Dr. Mairead Tagg who concluded that the appellant had indeed been the victim of horrifying sexual and psychological trauma. She was suffering from a form of post-traumatic stress disorder. The trauma had effectively overwhelmed and fragmented her ability to think clearly or rationally at the time when she killed the deceased. Dr. Anne Carpenter considered that the appellant's responses, as measured by certain tests, were wholly consistent with her having been the victim of abuse of the kind that she had described. The appellant had been in a state of learned helplessness. Victims of prolonged abuse were frequently unable to consider fully all the alternatives to remaining in the violent situation and their thinking processes became extremely limited. For these reasons the appellant had come to believe that the only possible way for her to leave her husband was to kill him.
 Neither of the psychologists was medically qualified. The only medical evidence led to support the plea of diminished responsibility came from Dr. Thomas White. He testified that towards the end of 1998 the appellant had been suffering from a clinical depression which would have warranted treatment with antidepressant drugs but would not have been sufficient to warrant her detention under Section 17 of the Mental Health (Scotland) Act 1984. He considered that the extent of her mood disturbance would not normally justify a report favouring diminished responsibility but, looking at the totality of the case, and looking at the absence of other factors and the absence of previous instability, he thought that this would weight the evidence in favour of diminished responsibility.
 The Trial Judge's Directions to the Jury
In his charge the trial judge dealt with the issue of diminished responsibility in this way:
"Now, that brings me to the necessity of explaining to you the concept of diminished responsibility and, I would - I'm sure you're listening to everything I say with care, but this is absolutely fundamental to this case - and I would ask you to pay very close attention to what I have to say.
The law recognises that there may be such a state of mind existing at the time of the commission of the crime, short of actual insanity, which may reduce the quality of an act from murder, in the absence of such a state of mind, to culpable homicide. That is an established principle of the law of Scotland.
Now, what is then diminished responsibility? What I'm going to do is to quote to you the classical definition of diminished responsibility and also to inform you about how that definition is to be viewed. And the classical definition runs like this - it is very difficult to put it in a phrase but it has been put in this way - that there must be aberration or weakness of mind, that there must be some form of mental unsoundness, that there must be a state of mind bordering on, though not amounting to, insanity, that there must be a mind so affected that responsibility is diminished from full responsibility to partial responsibility. In other words, the person in question must be only partially accountable for his or her actions and, running through the cases, that there is implied that there must be some form of mental disease. Now, that is the classic definition of the state of diminished responsibility and that definition, although it is of some age, survives in the law to this day. However, it has been said of that passage which I quoted to you, that it is to be read as a whole, with all of its elements, and it must be read together with the remark at the end of it, that running through all the cases, one can see that there must be some form of mental disease. Well, there it is, ladies and gentlemen, that is the definition of diminished responsibility.
Now, as regards diminished responsibility, I have to tell you that the burden of proving diminished responsibility lies not upon the Crown but on the accused. That's why at an earlier stage I said to you that, having explained the general principle about the onus of proof, I had to come back to the subject for this reason. So, if a plea of diminished responsibility is raised, as it has been here, the burden or task of proving diminished responsibility lies on the accused. However, in relation to that requirement, the standard of proof is different from that which the Crown must face in proving their case because it is enough if the accused brings evidence which satisfies you, the jury, of the probability of what they are called on to establish. So, the onus ... the standard of proof of diminished responsibility is, as we call it, on a balance of probabilities and not beyond reasonable doubt. So, if you were of the view that probably, as a matter of probability, the accused suffered from diminished responsibility at the relevant time, that would mean that she had discharged the onus upon her ....
Now, before I part with this subject, ladies and gentlemen, I feel bound to say this: during the course of the evidence of Dr. Thomas White there was some questioning of the witness about the requirements of a piece of legislation which is to be found in the Mental Health (Scotland) Act 1984 and, in particular, Section 17 of that Act. Now, that is a provision which stands quite separate from this case and it provides the definition of grounds upon which a person, any person, may be admitted to and detained in a hospital against their will. Now, I have to make clear to you that that provision is legally quite distinct from the issue of diminished responsibility and, although there was some evidence about that provision from Dr. White, you should not concern yourself with it because it is distinct and separate from the issue of diminished responsibility. The criteria which are set out in that section are different from the criteria for diminished responsibility and so you should not concern yourself with that in any way. In considering the issue of diminished responsibility you should proceed upon the basis of the definition which I have just given to you."
 The judge went on to mention certain parts of the evidence and indicated that, on the basis of all the circumstances, defence counsel was seeking to persuade the jury that the appellant had been, in counsel's words, "driven to the edge of insanity" by the actions of the deceased. His Lordship said that the suggestion was that, as a result of the deceased's treatment of her, the appellant had sunk into clinical depression, as spoken to by Dr. White. The judge described this as "really in a way the main plank of the defence plea" and added that the psychologists' evidence was relied on as elucidating both the behaviour patterns of people who had been the subject of abuse in a relationship with another person and the likely consequences of the abuse. He pointed out that the psychologists could not say that the appellant had developed mental illness - that was an area for the psychiatrists.
 The trial judge summarised various matters relating to diminished responsibility in a later passage of his charge:
"Well, there it is, ladies and gentlemen. That is the plea that is put before you, which the accused, accepting her onus to persuade you, asks you to accept as the basis for diminished responsibility. But the factors that I've mentioned so far would not alone be sufficient. The ingredient of some form of mental disease, which are the words that derive from the definition, is an essential one and you require, therefore, to consider whether you are satisfied that that element has been shown. In that connection the defence rely upon the evidence of Dr. Tom White, who gave evidence to you two days ago. He gave you his opinion which was, as I understand it, to the effect that at the material time Mrs. Galbraith was suffering from clinical depression, which can be seen as a mental disease or illness and, if you accept that evidence, then that ingredient is there. I have to say to you that, unless you were able to accept his evidence, you would not, in law, be entitled to sustain a plea of diminished responsibility because the element of some from of mental disease is an essential element in the plea."
 The Appellant's Contentions
At the outset we observe that the trial judge's directions were based on the law as laid down in H. M. Advocate v. Savage 1923 J.C. 49 as interpreted by this court in Connelly v. H. M. Advocate 1990 J.C. 349. Standing those authorities, his Lordship's directions were not open to criticism. Indeed Miss Scott did not suggest otherwise. Her contention was, rather, that in certain respects these authorities themselves contained erroneous, and unduly narrow, statements of the law on diminished responsibility. She was therefore attacking those authorities which, she submitted, had in turn led the trial judge to give unduly narrow directions in this case.
 The passage which Miss Scott criticised in Savage occurs in the directions that Lord Justice Clerk Alness gave to the jury (1923 J.C. at pp. 50 - 51):
"On the other hand, it appears, as I say, equally well established, although it has been variously phrased, that the state of mind of the prisoner may be such, short of insanity, as to reduce the quality of his act from murder to culpable homicide. It is very difficult to put it in a phrase, but it has been put in this way: that there must be aberration or weakness of mind; that there must be some form of mental unsoundness; that there must be a state of mind which is bordering on, though not amounting to, insanity; that there must be a mind so affected that responsibility is diminished from full responsibility to partial responsibility - in other words, the prisoner in question must be only partially accountable for his actions. And I think one can see running through the cases that there is implied - as Lord Stormonth-Darling in terms said in the case to which the Lord Advocate referred [H. M. Advocate v. Aitken (1902) 4 Adam 88 at pp. 94 - 95] - that there must be some form of mental disease. Well, ladies and gentlemen of the jury, that is a very difficult region of law. I have told you the kind of thing that it necessary. Aberration or weakness of mind; mental unsoundness; a state of mind bordering on insanity although not reaching it; a mind affected so that the responsibility is diminished from full responsibility to partial responsibility. That is the sort of thing that must be proved in order to establish that the crime which would otherwise be murder is only culpable homicide...."
That passage was interpreted by Lord Justice General Hope in the case of Connelly which Miss Scott also criticised. In Connelly counsel for the appellant had argued that the description of diminished responsibility given by Lord Alness had become out of date by 1990. The Lord Justice General said this (1990 J.C. at p. 358):
"I also reject counsel for the appellant's suggestion, which was an essential part of his argument, that the concept of diminished responsibility is so out of touch with modern medical science that it should be redefined. He made much of the fact that social conditions have changed since 1923 when the case of Savage was before the court and that the teaching and practice of psychiatric medicine has advanced considerably since those days. For my part, however, I do not think that changes of this sort provide grounds for a difference of approach. On the whole I should have thought that a greater knowledge and understanding of the human mind has made it somewhat easier for the concept in its present form to be applied, but I would not wish to form a concluded view on this point without a much closer examination of the subject than we have been able to undertake in this case. It is sufficient to say that, in my opinion, it would be quite wrong, as I think counsel was suggesting, to isolate one part of Lord Justice-Clerk Alness's description in Savage as expressing the concept and to discard the others, or to treat his description as listing four criteria which can be regarded as alternatives so that if one only - and in particular the last - is met that is enough. This would be to place far too much emphasis on one phrase which is, as it happens, the least helpful of all those in the description because it is so obviously tautologous. The passage must be read as a whole with all its elements, and it must be read together with the remark at the end that running through all the cases one can see that there must be some form of mental disease. In my opinion, it is the presence or absence of that particular characteristic, which has itself been variously described, which marks the borderline between what is acceptable and what is not. In H. M. Advocate v. Braithwaite [1945 J.C. at p. 57] Lord Justice-Clerk Cooper said: 'You will see, ladies and gentlemen, the stress that has been laid in all these formulations upon weakness of intellect, aberration of mind, mental unsoundness, great peculiarity of mind, and the like.'
It was with that in mind that he went on to say that it will not suffice in law merely to show that an accused person has a very short temper or is unusually excitable and lacking in self-control. In my opinion, the concept has been defined in terms which are sufficiently elastic or flexible to avoid the dangers of rigidity while at the same time preserving the doctrine from abuse. The question for the medical witness will be whether there is something in the mental condition of the accused which can properly be described as a mental disorder or a mental illness or disease. It is hard to see how the criteria for diminished responsibility could ever be met in the absence of evidence to this effect."
 Miss Scott's criticism of the law as laid down in these passages centred on two points.
 First, in Connelly the court had been wrong to interpret the passage from Lord Alness's charge as requiring to be "read as a whole with all its elements". This meant that all four of the criteria mentioned by Lord Alness - aberration or weakness of mind, mental unsoundness, a state of mind bordering on, though not amounting to insanity, a mind so affected that responsibility is diminished from full responsibility to partial responsibility - had to be met in any case before the defence would be established. If the passage were properly interpreted, she said, it could be seen that Lord Alness had simply been giving examples of the sort of thing which the accused required to prove. Provided that the accused proved something like one of these elements, that would constitute a sufficient basis for diminished responsibility. By requiring that all four elements should be established - and in particular that the accused should show that his state of mind had bordered on insanity - the court in Connelly had not only misinterpreted the meaning of the passage in Savage but had, in consequence, unduly narrowed the scope of the defence.
 Secondly, Miss Scott argued, Lord Alness had himself been wrong to say that he thought that one could see running through the cases a requirement "that there must be some form of mental disease". For this, Lord Alness had referred to an observation of Lord Stormonth-Darling in H. M. Advocate v. Aitken 4 Adam at pp. 94 - 95: "[The rule] could only be applied if a jury were satisfied that there was something amounting to brain disease". It is to be noted, as Lady Cosgrove pointed out in the original hearing, that when importing this requirement Lord Alness substituted "mental disease" for "brain disease." Miss Scott said that "mental disease" was not a term which psychiatrists would tend to use today. But, in any event, it seemed quite inappropriate to say that someone who had been born with mental handicap was suffering from "mental disease". Yet, some of the cases before Savage showed that such a condition could form the basis for a plea of diminished responsibility. In Connelly Lord Hope had said that there had to be something that could be described as "a mental disorder or a mental illness or disease". It might well be that he had wished in this way to introduce some flexibility into the mental disease requirement. But, when giving the opinion of the court in Williamson v. H. M. Advocate 1994 J.C. 149 at p. 152 G, the Lord Justice Clerk (Ross) had excluded any possibility of flexibility:
"We do not agree that the expressions are used disjunctively. In the context in which they are used we are of the opinion that the two expressions do not express alternatives but are referring to the same thing; they are merely using different words to express the same concept."
 In the present case, Miss Scott argued, the requirement in the trial judge's directions to the jury that there should be a "mental disease" had had two related effects. First, it meant that they had to find medical evidence of a mental disease. In concrete terms, the jury had to accept Dr. White's evidence that the appellant was suffering from clinical depression and that it was of such a degree as could give rise to diminished responsibility. Unfortunately for the defence, Dr. White had been hesitant in expressing that view. The second effect was the obverse of the first. Even if the jury accepted the appellant's account of being abused by the deceased, they could not find a sufficient basis for diminished responsibility in the evidence of the two psychologists, that she was suffering from a recognised condition of post-traumatic stress disorder or of learned helplessness which would have affected her ability to see any solution to her predicament other than killing her husband. On a proper application of the law, the jury should have been directed that they could return a verdict of culpable homicide if they accepted the appellant's evidence of abuse and the psychologists' evidence as to the effect of such abuse.
 The Position of the Crown
As the court recorded in paragraphs 8 and 12 of the opinion of 7 June, at the original hearing of the appeal the Advocate Depute submitted that, when properly interpreted, the decision in Connelly did not require that every single part of the Savage test should be met in every case. Only two things were necessary: that the accused's responsibility should have been diminished and that this should have been due to mental disease. In deciding whether the accused's responsibility was diminished, the jury required to take the Savage factors together and to read them as a whole and in their entirety. This applied to the requirement that the accused's state of mind should border on insanity: the jury would have to consider and weigh that element but it might not in itself be decisive. The court, as then constituted, had difficulty in understanding how the jury were meant to carry out the exercise described by the Advocate Depute.
 When the hearing before this larger court began, the Solicitor General, who now appeared for the Crown, indicated that the position of the Crown had in the meantime changed in two respects. First, he accepted that, on a proper interpretation, in Connelly the court had indeed held that all the four elements in the Savage test had to be satisfied before there could be diminished responsibility. This gloss misrepresented what Lord Alness had said in Savage: he had simply given a number of examples of what was required. The Crown not only accepted that the court in Connelly had misunderstood what Lord Alness had said but also that, as a matter of substance, the cumulative approach derived from that misinterpretation was wrong and should not be followed. In this respect we should revert to the interpretation of Savage as it had been understood before Connelly and Connelly should be overruled. In addition, the Solicitor General indicated that the requirement in Savage that there should be a "mental disease" was too restrictive. It was, he said, hard to see how certain of the examples in the earlier cases, such as aberration or weakness of mind, would fall, or would always fall, within such a description. It followed that, in so far as Williamson held that the only kinds of mental disorders which could be taken into account were mental diseases or illnesses, it too had been wrongly decided.
 In the light of those important concessions the Solicitor General went on to announce that the Crown now conceded that the trial judge had misdirected the jury in the present case. If the court accepted that the Crown concessions had been correctly made, we should allow the appeal but he would ask us to grant authority to the Crown to bring a new prosecution.
 Despite the Crown concessions, we heard detailed submissions on the third ground of appeal since we had ourselves to be satisfied as to the true legal position before we could depart from the pre-existing decisions of this court and allow the appeal. As will be apparent, however, the concessions transformed the way the appeal was conducted. Both sides now agreed that Connelly was wrongly decided and that there could be diminished responsibility without the accused suffering from a "mental disease". In the event, when the Solicitor General came to address the court on behalf of the Crown, he was content to adopt what Miss Scott had said in criticism of the previous decisions without modifying it in any way. As was all too apparent, however, both counsel found it much easier to tear down the somewhat fragile structure that our predecessors had erected than to suggest what we should raise up in its place. In the end the Solicitor General said that the matter was one of difficulty and that, if the suggestions of counsel did not find favour, we should simply have to do what we willed. Wafted on some Continental zephyr, the doctrine that the court knows the law had, apparently, reached our shores. So, duly admonished, we set about our task.
 "Diminished Responsibility"
When courts use the term "responsibility", they are generally referring to responsibility in law. For instance, children under a certain age and persons who are regarded as "insane" are not responsible for their actings according to our criminal law. As is obvious from the fact that the age of criminal responsibility varies from system to system and can be changed by statute, "responsibility" is a legal, rather than a medical or psychological, concept. Similarly, "diminished responsibility" is a legal, as opposed to a medical or psychological, concept.
 This concept of "diminished responsibility" is often thought to have entered our law in Lord Deas's charge to the jury in H. M. Advocate v. Dingwall (1867) 5 Irv. 466. In one sense that is, of course, correct. But in another sense it can mislead. When the term is in common currency today in the law of both Scotland and England, we may easily imagine that "diminished responsibility" has been part of the everyday linguistic furniture of our law since the time of Lord Deas. But that is not so.
 The term "diminished responsibility" is indeed found as early as 1873 in the preface to the third edition of Francis Wharton's Treatise on Mental Unsoundness embracing a General View of Psychological Law, p. xiv, an American work purchased by the Advocates Library. Wharton says that the idea of "diminished responsibility" is already familiar to the law in cases of "abnormal excitement". He points out that, in German, the term itself was to be found in the Austrian and Bavarian criminal codes, which recognised degrees in penal responsibility: "verminderte Zurechnungsfähigkeit" attracted a lesser penalty. Today, for doctrinal reasons, the heading of the equivalent Article 21 of the German Strafgesetzbuch uses the idea of "verminderte Schuldfähigkeit" (diminished culpability). Where the article applies, the court can impose a more lenient sentence.
 The term "diminished responsibility" had therefore been coined by 1873 at the latest. In Scotland, however, according to the reported cases at least, the first judge to use the actual phrase was Lord Justice General Normand in Kirkwood v. H.M. Advocate 1939 J.C. 36 at p. 37, narrating that the appellant's counsel had tendered "a plea of guilty of culpable homicide on the ground of his diminished responsibility". Lord Normand was in fact reflecting the words used by the Dean of Faculty, that the appellant "was of diminished responsibility" (Transcript of the proceedings in Edinburgh High Court on 8 November 1938, p. 58, 1939 Justiciary Papers No. 5, Advocates Library). Thirty years earlier, the phrase, as such, had been found in the reporter's headnote, rather than in Lord Guthrie's charge to the jury, in H. M. Advocate v. Edmonstone 1909 2 S.L.T. 223. Lord Guthrie told the jury that the man's mind had to be affected to such an extent that his responsibility was diminished from "full responsibility to partial responsibility" (1909 2 S.L.T. at p. 224). Other cases confirm that the terminology was for long unsettled. In Savage Lord Alness adopted Lord Guthrie's terminology and spoke of "partial responsibility". Ten years later, in Muir v. H. M. Advocate 1933 J.C. 46 at p. 47, Lord Justice General Clyde used the phrase "lessened responsibility", while both the Lord Justice Clerk (in his unreported charge to the jury, Transcript of proceedings in Dumfries High Court, 13 April 1933, p. 200, 1933 Justiciary Papers No. 8, Advocates Library) and Lord Sands (1933 J.C. at p. 50) referred to "partial insanity". In Kirkwood v. H. M. Advocate 1939 J.C. at p. 39 Lord Justice General Normand, having referred to the plea based on "diminished responsibility", seems to have preferred the term "impaired responsibility". In H.M. Advocate v. Braithwaite 1945 J.C. 55 at p. 57 Lord Justice Clerk Cooper spoke of "this defence of diminished responsibility" but, a year later, he referred to "reduced responsibility": Russell v. H. M. Advocate 1946 J.C. 48. In the following months, in Carraher v. H. M. Advocate 1946 J.C. 108, both Lord Russell at the trial (1946 J.C. at p 110) and Lord Normand on appeal (1946 J.C. at p. 115) fastened on the term "diminished responsibility", while Lord Normand used it again in Caldwell v. H.M. Advocate 1946 S.L.T. (Notes) 9. From that time onwards it seems to have taken root.
 The late appearance of the term "diminished responsibility" in the cases is due to no accident of reporting. The phrase is not to be found in Anderson's Criminal Law (second edition, 1904) and has no place in the second, third or fourth editions of the practitioner's vademecum, Macdonald's Criminal Law. It makes its entry as late as the fifth edition, published in 1948, after Kirkwood, Braithwaite and the other cases. Interestingly enough, the editors use it (pp. 96 - 97) to cover both cases of provocation and cases where the mental state of the accused borders on insanity. Even in England the phrase "diminished responsibility" does not actually appear in the body of Section 2 of the Homicide Act 1957 but finds a toe-hold in the side-note.
 If the terminology used by the judges was unsettled, this was because they had not really settled the precise nature of the plea which they were describing. It was clear enough, from the time when Dingwall came to be accepted, that in certain circumstances the accused's mental state meant that the jury could return a verdict of culpable homicide, even though the nature of the act committed by the accused would otherwise have justified his conviction for murder. But the rationale for doing so was put in different ways. For instance, in 1867 in Dingwall (5 Irv. at pp. 479 - 480) Lord Deas based his direction on the idea that culpable homicide included "murder with extenuating circumstances" and that the state of mind of a prisoner might be "an extenuating circumstance". Some fourteen years later, in H. M. Advocate v. Ferguson (1881) 4 Coup. 552 at p. 558 Lord Deas was able to refer to the reduction of murder to culpable homicide in such cases as a "doctrine" which drew a distinction similar to that between murder in the first and second degree in other systems. He used the same analogy in H. M. Advocate v. Brown (1882) 4 Coup. 596 at p. 597. On the other hand, in H. M. Advocate v. Tierney (1875) 3 Coup. 152 at p. 166, Lord Ardmillan appears to justify a possible verdict of culpable homicide on the basis that the accused's "control over his own mind might have been so weak as to deprive the act of that wilfulness which would make it murder". In H. M. Advocate v. Smith (1893) 1 Adam 34 at p. 52 Lord Maclaren told the jury that, if the accused's mind had been rendered unstable by a continued course of persecution for a year, he might really be physiologically unable to resist provocation at the last "and therefore, in that sense, might be to some extent excusable".
 Since the theoretical basis for allowing a jury to return a verdict of culpable homicide on account of the accused's mental state was itself unclear, it is not perhaps surprising to find that, in the same period, the judges did not choose to describe very clearly the kind of mental state which could have that effect. In the cases before Savage we find: a "mind weakened by successive attacks of disease" in the shape of sunstroke, subsequent epileptic fits and delirium tremens (Dingwall 5 Irv. at p. 479), "the mental condition... of an imbecile... weak-minded from childhood" (H. M. Advocate v. M'Lean (1876) 3 Coup. 334 at p. 335), a weak or diseased mind due to delirium tremens brought on by drinking (H. M. Advocate v. Granger (1878) 4 Coup. 86 at p. 110), "weakness of mind" due to a feeble intellect in someone who had seven years previously been admitted to a mental hospital on grounds of insanity (Ferguson 4 Coup. at pp. 557 and 558), a "weak understanding" (H. M. Advocate v. Gove (1882) 4 Coup. 598 at p. 599), a "weak mind" in a woman in depressed spirits after visiting her mother in a mental hospital (Brown 4 Coup. at p. 597), a mind rendered unstable by persecution (Smith 1 Adam at p. 95), "mental unsoundness" (H. M. Advocate v. M'Clinton (1902) 4 Adam 1 at p. 25), a mind morbidly affected by brooding over a wife's unfaithfulness (Aitken 4 Adam at p. 95) and faculties enfeebled by fits (Edmonstone 1909 2 S.L.T. at p. 224).
 The Four Savage Criteria
In Savage, in an effort to help the jury, Lord Alness tried to make sense of this confused picture. And, even though he did not use the actual term, his directions have become the locus classicus for modern judges giving directions on "diminished responsibility". Lord Alness told the jury that the state of mind required to give rise to the defence had been put "in this way" and he then gave four criteria. The first is "aberration or weakness of mind". As we have just noted, weakness of mind, expressed in various ways and arising from a variety of causes, is a condition which is found in several of the cases. The phrase "aberration of mind" is not, on the other hand, used in any of the trial judges' directions but is to be found in the reporter's rubric in M'Lean and Granger. Moreover, in Granger, in dealing with a defence plea after the verdict, Lord Deas does indeed refer back to the rubric in the earlier case (4 Coup. at p. 111). The second criterion to which Lord Alness refers is "some form of mental unsoundness", which derives from M'Clinton. The third is "a state of mind bordering on, though not amounting to, insanity" - which seems to correspond to the situation, envisaged by Lord Deas in M'Lean, where there was an "approximation" to insanity. The last of the criteria is "a mind so affected that responsibility is diminished from full responsibility to partial responsibility" which - as we have already noticed - is taken from Lord Guthrie's charge in Edmonstone.
 As we have shown by identifying the sources of the criteria, Lord Alness has done exactly what he professes to do: he has put before the jury formulae which judges in earlier cases had used in directing juries. In these earlier cases, there is a lack of consistency: different judges use different formulae and none of them uses all four of the criteria. Lord Alness does not suggest that any of these formulae was incorrect: on the contrary, he draws attention to them because he considers that they may help the jury to understand what it is that they must find if they are to return a verdict of culpable homicide. Of course, in putting these various tests to the jury, Lord Alness repeatedly uses the word "must" - there must be aberration or weakness of mind, there must be a form of mental unsoundness, etc. - because that is how, in substance, the particular test was framed in the context of the original judge's charge. But, by repeatedly using the word "must", Lord Alness did not mean that the jury in Savage required to be satisfied that the accused's state of mind satisfied all of these tests. Rather, he was simply explaining to the jury "the kind of thing that is necessary", "the sort of thing that must be proved" - the (deliberate) imprecision of his direction reflecting the somewhat fluid manner in which the test had been expressed in the earlier cases.
 This becomes even clearer when we look at a later passage in the Lord Justice Clerk's charge. After referring to the relevant evidence, Lord Alness told the jury to consider whether the accused had proved to their satisfaction that at the relevant time "his mental state was unsound, that he was in a state of mental aberration, and not fully responsible for his actions". In formulating that test, Lord Alness adopted an eclectic approach: he took the second criterion (from M'Clinton), the part of the first criterion derived from the rubric in M'Lean and the fourth criterion (from Edmonstone). Most notably, perhaps, he did not direct the jury, in terms of the third criterion, that the accused's state of mind had to border on insanity. The operative direction given by Lord Alness demonstrates, therefore, that he himself did not intend to treat the criteria as cumulative requirements, all of which must be satisfied. Equally clearly, when Lord Cooper referred to the passage from Savage as giving as explicit and clear a statement as he could find "of the sort of thing which you have to look for" (Braithwaite 1945 J.C. at p. 57), he cannot have considered that a state of mind had to satisfy all four criteria before it could found a plea of diminished responsibility.
 We are therefore satisfied that in Connelly the court were wrong to insist that the passage in Savage had to be read as a whole and that all of the criteria had to be met. The decision in Connelly should, accordingly, be overruled and the trial judge's direction in this case must be regarded as unsound.
 The "Mental Disease" Requirement
We turn now to Miss Scott's submission that it was wrong to say that the plea of diminished responsibility could not be established unless the accused was suffering from a "mental disease" at the relevant time. Lord Alness thought that this requirement could be detected in the earlier authorities and, since Williamson, it has been laid down as an absolute requirement.
 Although Miss Scott did not explore the facts of Savage and they are not set out in any of the reports, it is difficult to understand what Lord Alness was really telling the jury without having them in mind. As the accounts in The Edinburgh Evening News 21 May 1923 and The Scotsman 22 May 1923 show, the trial in Savage was completed within a single day and the evidence was not extensive. For present purposes, it can be summarised fairly briefly.
 The deceased, Mrs. Grierson, lived with a Mr. Tillett in a tenement in Leith. Mr. Tillett left for work shortly before ten in the evening and about a quarter of an hour later Savage came to the door and was admitted. According to a witness who was in the house for quite a considerable time, he appeared to be sober and quiet. But at about one o'clock in the morning the deceased, in a state of agitation, went to a neighbour's house and the neighbour returned with her to her own house. There she found Savage sitting smoking. When the deceased spoke to Savage, he said "If you don't hold your tongue, I will cut your head off your body." The neighbour went to put on more clothes and Savage closed the door behind her. Sounds of a struggle were heard, with the deceased screaming for help. Her screams stopped suddenly. About five minutes later, Savage came out and the neighbour asked him what he had done. He replied "If you don't clear out, I'll do the same to you." He raised his hand in which something glittered. Savage went downstairs and the neighbour went into the flat where she found the deceased lying on the kitchen floor. Savage had cut the deceased's throat with a razor and she died of the injury.
 Savage was seen at about 6.20 that morning, bloodstained, in a dazed condition and smelling strongly of methylated spirits. When examined by a doctor later that day, he was getting over the effects of drink. The warder of the lodging-house where he lived said that Savage was rarely sober and you could smell methylated spirits a mile off. He was a very peculiar man in company. He was very violent and seemed to lose all control of himself. A defence witness said that when he got a certain amount of liquor, the accused had no control of himself and, on one occasion, he had come up as if to shake hands with the witness, but had struck him with a poker. Another defence witness said that Savage was a very peculiar man who took methylated spirits which left him irresponsible for his conduct. On one occasion he threw himself into the Water of Leith. A medical witness, Dr. M'Alister, expressed the opinion that on the day in question Savage was not responsible for his actions and was incapable of knowing the nature and quality of the action with which he was charged. He was also incapable of forming the specific intention to do serious injury to the deceased.
 In his charge to the jury Lord Alness left them to consider both the issue of insanity and the issue of "partial responsibility". Presumably, the evidence of Dr. M'Alister would have been the possible basis for an insanity verdict. Not surprisingly, the jury rejected that. Savage must have hoped to establish his "partial responsibility" plea by proving that he had been drunk when seen some hours later and that not only was he in the habit of drinking methylated spirits but, when he did so, he tended to lose control of his actings. The jury must have been asked to draw the inference that, at the time when he killed the deceased, Savage had been drunk and had, as a result, been only partially responsible for his act. This emerges from the Lord Justice Clerk's remark to the jury (1923 J.C. at p. 51) that they would not need to consider the difficult question of the four criteria, if they accepted the Lord Advocate's contention that Savage had not proved that he was drunk. In the end, the jury convicted Savage of murder.
 From the standpoint of today the defence plea might, of course, appear somewhat surprising. In Brennan v. H. M. Advocate 1977 J.C. 38 a Full Bench held that self-induced intoxication cannot found a plea of diminished responsibility. But, in doing so, they overruled the decisions in H. M. Advocate v. Campbell 1921 J.C. 1 and Kennedy v. H. M. Advocate 1944 J.C. 171. In 1923, when Lord Alness presided in Savage, the principal authorities, including Campbell, supported the view that an accused's drunkenness, even though self-induced, could be a basis for returning a verdict of culpable homicide rather than of murder. That verdict would be appropriate if the jury were satisfied that, in his drunken state, the accused had not had the intention to kill or to do serious injury to the victim. In connexion with that argument, counsel in Savage referred (1923 J. C. at p. 49 n. 1), for example, not just to Campbell but also to D.P.P. v. Beard  A.C. 479, which had been applied in Campbell, and to the earlier decision of Lord Justice Clerk Macdonald in H. M. Advocate v. Kane (1892) 3 White 386. As Lord Alness explained to the jury (1923 J.C. at p. 50), the fact that a man was drunk was "not sufficient reason to excuse him from the consequences of his crime" (emphasis added) but the state of his mind might be such as to reduce the quality of his act from murder to culpable homicide. We note, en passant, that the authorities cited in support of the plea of "partial responsibility" included Beard, from a system where diminished responsibility was unknown to the common law.
 The evidence in Savage did not suggest, and the defence did not contend, that the accused was a man whose mind had been in some way permanently affected by drinking methylated spirits. Rather, the contention was that he had been drunk at the time when he killed the deceased and, for that reason, he had been only partially responsible. He should therefore be convicted of culpable homicide rather than of murder. Lord Alness did not withdraw the plea from the jury's consideration. He must therefore have considered that a verdict of culpable homicide would have been open to the jury, applying the directions which he gave them, on the most favourable construction of the evidence. That being so, it does not appear to us that, when he referred to the need for a "mental disease", Lord Alness can have been using that expression in the narrow sense in which it was applied in later cases culminating in Williamson. Apparently, the effects of drinking, in the particular case of Savage at least, could have fulfilled any requirement that there should be "mental disease". We are accordingly satisfied that in the later cases the court interpreted this requirement more strictly than Lord Alness would have intended. We cannot part from Savage without noticing the remarkable fact that the passage from the Lord Justice Clerk's charge has remained authoritative, even though his actual directions to the jury appear to be inconsistent with the decision in Brennan.
 No explication de texte, however rigorous, can hope to conjure up an outline of the law of diminished responsibility. It may remove certain erroneous glosses. But, when they are stripped away, the Lord Justice Clerk's guidance to the jury remains nothing more than the kind of purely practical guidance suitable to such an occasion. He did not analyse the matter in any detail. Nor was there, in those days, an Appeal Court to do so. Whatever the merits of the passage may have been in its original context - and, given the nature of the actual issue which the jury had to decide, even these may be debatable - it is not particularly illuminating in other, very different, cases such as the present. As Lord Cameron of Lochbroom said during argument at the first hearing, there is a risk that, in some cases, quoting the passage may amount to little more than reciting a mantra. Almost certainly, the passage has proved popular with judges because of the difficulty of explaining the matter any more clearly. Lord Goddard L.C.J. spotted this (R. v. Spriggs  1 Q.B. 270 at p. 274) and we are acutely aware of the difficulty ourselves. The observations that we now go on to make about the underlying principles of our law are, accordingly, somewhat tentative. They may have to be modified or refined in the light of experience in subsequent cases.
 Diminished Responsibility as a Legal Concept
As we pointed out above, responsibility and diminished responsibility are legal, rather than medical or psychological, concepts. In our law diminished responsibility applies in cases where, because the accused's ability to determine and control his actings is impaired as a result of some mental abnormality, his responsibility for any killing can properly be regarded as correspondingly reduced. The accused should, accordingly, be convicted of culpable homicide rather than of murder. Since this conclusion as to his reduced level of responsibility is a legal conclusion, it is not the function of the witnesses, lay, psychological, medical or psychiatric, to say whether an accused's responsibility can properly be regarded as diminished. Rather, they give evidence as to the accused's mental state. It is then for the judge to decide whether, at its highest, this evidence discloses a basis upon which the law could regard the accused's responsibility as being diminished. If the judge decides that the evidence could not meet that test, then the defence must be withdrawn from the jury's consideration. If, on the other hand, the judge decides that, at its highest, the evidence could justify the conclusion in law that the accused's responsibility was diminished, then the judge must direct the jury that, depending on whether or not they accept that evidence, they can return a verdict of culpable homicide. It will then be for the jury to consider the evidence and, depending on their view of it, to decide whether, if convicting, to convict the accused of murder or of culpable homicide.
 As this simple analysis shows, the law recognises a class of states of mind in respect of which an accused's responsibility is diminished. In other words, if the accused's state of mind was of that kind when he killed the deceased, then the law recognises that he was not fully responsible for his act and, for that reason, holds that he should be convicted of the less serious crime of culpable homicide. In his first three criteria in Savage Lord Alness gave examples of states of mind which the law had recognised as being members of this general class of states of mind where the law would hold that a person's responsibility was diminished. The fourth, tautologous, criterion was really an unsatisfactory attempt to define this general class - and was, as such, different in kind from the first three criteria. The critical question for the law of diminished responsibility is to see where the limits of the general class lie. We do not pretend to give a definitive answer to that question in this case, beyond saying that the law does indeed set limits, two at least of which are already marked with bright lines.
 First, since Brennan, our law has held that no mental abnormality, short of actual insanity, which is brought on by the accused himself taking drink or drugs or sniffing glue, will lessen his responsibility for his acts and omissions or for their results. Secondly, psychologists and psychiatrists acknowledge the existence of a condition described as psychopathic personality disorder. What, exactly, its causes and effects may be we need not determine because it has for all practical purposes been settled, since Carraher, that our law does not regard such a disorder as a basis for holding that the accused's responsibility for his acts is diminished. The decisions in Brennan and Carraher thus mark out territory into which diminished responsibility does not extend in our law. Moreover, since the court is fixing the boundaries of a legal doctrine, there is no inconsistency between the psychiatrists' recognition of psychopathic personality disorder and the decision of the court that the law does not recognise such a disorder as a basis for diminished responsibility. That is a matter of legal policy for the court, and ultimately for the legislature, and not for psychiatrists or psychologists. Similarly, there may be other disorders recognised by such experts which, for sound policy reasons, the court will exclude from the ambit of diminished responsibility.
 The Basis of Diminished Responsibility
It is, of course, impossible to attempt to describe the ambit of the doctrine of diminished responsibility without even attempting to describe the operation of the doctrine itself. A common theme in the cases where judges have left the issue to the jury is that they involve some abnormality of the accused's mind. While philosophers continue to debate the timeless questions - about the nature of the relationship between mind and body and about the extent to which individuals have control over their actions - our law proceeds on the basis that an adult person of sound mind has sufficient control over his acts, and over his omissions to act, as to be responsible for them in law. Criminal acts and omissions are punished accordingly. (This applies also, of course, to children over the age of criminal responsibility but, for ease of exposition, we include them in the term "adult".) For a variety of reasons, however, an adult's mind may be affected, either permanently or for a certain period, in such a way that it does not work like the mind of a normal adult. The law takes account of this. In extreme cases, the person's mind can be affected so extensively that the law treats him as being insane and, therefore, as not being responsible at all for his acts and omissions. In other cases, the operation of the person's mind is affected to a lesser degree so that he remains able to determine or control his acts and omissions but his ability to do so is impaired and is not that of a normal adult. Where a person's mind is so affected to a substantial degree, according to our law he is not to be treated as fully responsible for his acts and omissions: his responsibility is diminished.
 Because the individual is not fully responsible in law for what he does when his mental state is substantially impaired, the law mitigates the punishment which it deems appropriate for his criminal acts. In the case of murder, however, the sentence has always been fixed by law and cannot be varied by the judge according to the circumstances. Formerly the only sentence was death. Now it is life imprisonment. Therefore, to permit the necessary mitigation of punishment in cases where the prisoner killed someone at a time when his state of mind was such that, according to our law, he was not fully responsible for his act, he is to be convicted of culpable homicide, a lesser crime for which the judge may determine the level of punishment. We heard no detailed submissions on the matter of attempted murder and therefore go no further than to record that, in H.M. Advocate v. Blake 1986 S.L.T. 661 at p. 663 C, Lord Brand directed the jury that, if they found diminished responsibility established, their verdict would be "guilty of assault under deletion of attempted murder on the ground of diminished responsibility". In R. v. Smith  1 A.C. 146 at p. 207 A Lord Millett captures the spirit of the law relating to murder when he says that in a case of diminished responsibility
"the jury are invited to say: 'You can't really call it murder: the poor man wasn't fully responsible for his actions.' The defence is the response of a civilised society to inadequacy."
 It is important to notice that diminished responsibility does not come into play unless the effect on the person's mind is substantial. That requirement emerges, for instance, from Lord Sands's reference in Muir to "great peculiarity of mind" (1933 J.C. at p. 49) and is reflected in Section 2 of the English Homicide Act 1957 which refers to such abnormality of mind as "substantially" impaired the accused's mental responsibility at the time of the crime. Provided, however, that the impairment of the functioning of the mind was substantial, that is sufficient. It is neither necessary nor appropriate to stipulate that the accused's mental state should have bordered on insanity.
 Of course, where a person's mental state does indeed border on what the law regards as insanity, it is likely that the law will regard his responsibility as diminished. And in the, nowadays, comparatively rare case where the accused lodges a special defence of insanity at the time of the killing, it may well be appropriate to direct the jury that, if they find that the accused was not insane, they should nevertheless go on to consider whether his mental state bordered on insanity - in which event they would convict of culpable homicide. In such a case the judge will have given directions on the legal definition of insanity and, in that context, the jury should be in a position to understand and apply a direction about a state of mind bordering on "insanity". In other cases, such as the present, where the jury have not been given a direction on insanity, it is hard to know how they can understand or apply such a direction. Perhaps for that reason, in England and in the Commonwealth, when the courts give such a direction, they assert that the reference must be to "a mental state which in popular language (not that of the M'Naghten Rules) a jury would regard as amounting to partial insanity or being on the border-line of insanity" (R. v. Byrne  2 Q.B. 396 at p. 404 per Lord Parker L.C.J.) or to "insanity in its broad popular sense" (Rose v. The Queen  A.C. 496 at p. 508 per Lord Tucker, giving the advice of the Privy Council in an appeal from the Bahamas). With respect, we have difficulty in understanding what such a popular conception of insanity would be or why the legislature should have chosen to incorporate it into Section 2 or the equivalent colonial legislation. In any event, we are satisfied that no such solution is open in our law. To try to overcome the difficulty, in Lindsay v. H. M. Advocate 1997 J.C. 19, the trial judge, Lord Hamilton, incorporated a direction on insanity into his directions on diminished responsibility, even though there was no suggestion that the accused in that case was actually insane (1997 S.L.T. 67 at p. 69 B - D). One danger is, of course, that any such direction will further complicate the jury's task.
 More importantly, in England the Court of Appeal have held that a direction that the accused's state of mind should border on insanity may on occasions be so inappropriate as to amount to a misdirection. In R. v. Seers (1984) 79 Cr. App. R. 261 they accordingly quashed a conviction for murder, where such a direction had been given in the case of an accused who, according to the prison medical officer, had been suffering from chronic reactive depression. Even if they accepted the medical officer's evidence, the jury might still not have thought that the accused could properly be described as "partially insane or on the borderline of insanity". We find the court's reasoning compelling.
 The perception that the accused's state of mind must border on insanity has had a further undesirable consequence. Some doctors, at least, have felt that diminished responsibility could apply only where an accused could properly be detained in terms of Section 17 of the Mental Health Act. That misconception
was shared, apparently, by the Advocate Depute at the appellant's trial who cross-examined Dr. White on that basis. The trial judge had to direct the jury, in a passage quoted in paragraph 9, that the Section 17 test had no role to play in their consideration of diminished responsibility.
 For these reasons, it will rarely be helpful to refer to "a state of mind bordering on insanity" except in cases where a real question arises as to whether the accused was insane at the time when he killed the deceased. In other cases, it will be sufficient and preferable to direct the jury that the effects of any abnormality of mind must be substantial.
 Different Forms of Abnormality
The inadequacy or abnormality to which, as Lord Millett says, society responds may take a number of forms. In other words, an individual's mind may work differently from the mind of a normal person in more than one way and for more than one reason. The abnormality may mean, for example, that the individual perceives physical acts and matters differently from a normal person. In some cases he may suffer from delusions. Or else it may affect his ability to form a rational judgment as to whether a particular act is right or wrong or to decide whether to perform it. In a given case any or all of these effects may be operating and may impair the accused's ability to determine and control his acts and omissions. The cases of diminished responsibility recognised by the law in the past do indeed involve abnormality of mind of this kind and, therefore, fall within this general description. The law responds in this way, however, because it recognises that the individual is to be pitied since, at the relevant time, he was not as normal people are. There was unfortunately something far wrong with him, which affected the way he acted. By contrast, the law makes no such allowance for failings and emotions, such as anger and jealousy, to which any normal person may well be subject from time to time. They do not call for the law's compassion. Rather, we must master them or else face the consequences:
"... it will not suffice in law for the purpose of this defence of diminished responsibility merely to show that an accused person has a very short temper, or is unusually excitable and lacking in self-control. The world would be a very convenient place for criminals and a very dangerous place for other people, if that were the law" (Braithwaite 1945 J.C. at pp. 57 - 58 per Lord Justice Clerk Cooper).
 The Aetiology of the Abnormality
Abnormality of mind can spring from a variety of causes. Again, we can see this in the cases on diminished responsibility which we have examined. Suggested causes for the accused's abnormality of mind include, for instance, sunstroke, chronic drinking bringing on delirium tremens, low intelligence and depression. But these are merely examples and it is not difficult to give others which might also be relevant. Indeed in H. M. Advocate v. Ritchie 1926 J.C. 45 at p. 49 Lord Murray attempted a brief catalogue of conditions which could affect a person's responsibility:
"The most familiar case is where reason has been upset and the person is, in common parlance, out of his mind, a condition which may be permanent or passing. This condition may be induced by various causes. It may be congenital; it may be induced by illness, fever, palsy, accident, injury, or shock; all these may induce a condition in which, in popular language, a man is 'not fully responsible for his action.'"
We can add other, more specific, examples. Even in the present state of medical knowledge, it is plain - as Lord Murray perceived - that many organic disorders in some way affect the operation of the brain and so lead to some mental abnormality which could be of relevance in the present context. For instance, head injuries and brain tumours may affect the patient's consciousness and lead to personality changes of various kinds. Strokes may result in patients becoming more aggressive. Disorders of the thyroid are known to have mental manifestations, while hypoglaecemia is well known to affect people's behaviour, sometimes making them disinhibited and aggressive. Many drugs administered for therapeutic purposes are known to have side-effects of various kinds: some will induce drowsiness or confusion, while others will lead to euphoria and still others to depression. The mental abnormalities caused in these different ways could well impair an accused's ability to determine or control his acts and omissions, just as much as the conditions springing from the causes specified in the earlier case law. But a lay person, at least, might hesitate to say that someone suffering from one of these conditions was suffering from a "mental disease" or "mental illness". This confirms that these terms may indeed be too narrow to describe the range of possible conditions in respect of which the doctrine of diminished responsibility may apply. In this respect the approach prescribed in Connelly and Williamson is, as a matter of substance, unduly restrictive. While we have chosen to highlight conditions brought on by organic disorders, there are, of course, other recognised conditions, such as schizophrenia and certain kinds of depression, which do not appear - in the light of medical knowledge today, at least - to have an organic cause but which result in mental abnormality of a kind that may be relevant for the purposes of diminished responsibility.
 If the law has accepted that external causes, such as "strokes of the sun" and head injuries, may give rise to a relevant mental abnormality for the purpose of diminished responsibility, we can see no reason in principle why a recognised abnormality caused by sexual or other abuse inflicted on the accused might not also be relevant for the same purpose. We stress, of course, that the abuse must result in some recognised mental abnormality. Subject to that important qualification, we again see no reason in principle why evidence of such a condition could not be given by those, such as psychologists, having the appropriate professional expertise, even though they were not medically qualified. Since there is to be a new trial, we say nothing about the circumstances of this case.
In this opinion, in addition to examining the cases of Savage, Connelly and Williamson, we have been concerned to clarify certain elements in the plea of diminished responsibility. We can summarise our conclusions on that matter in this way:
1. Where, on the facts found proved by the jury, the law holds that the accused's responsibility was diminished at the time when he killed his victim, the proper course is for the jury to convict the accused of culpable homicide.
2. But, precisely because diminished responsibility is a legal concept, it is for the trial judge to determine whether there is evidence on which the jury would be entitled to convict the accused of culpable homicide rather than of murder, on the ground of diminished responsibility. In determining that issue, the judge must consider the kinds of issue that we have discussed. In essence, the judge must decide whether there is evidence that, at the relevant time, the accused was suffering from an abnormality of mind which substantially impaired the ability of the accused, as compared with a normal person, to determine or control his acts.
3. The abnormality of mind may take various forms. It may mean that the individual perceives physical acts and matters differently from a normal person. Or else it may affect his ability to form a rational judgment as to whether a particular act is right or wrong or to decide whether to perform it. In a given case any or all of these effects may be operating.
4. The abnormality must be one that is recognised by the appropriate science. But it may be congenital or derive from an organic condition, from some psychotic illness, such as schizophrenia or severe depression, or from the psychological effects of severe trauma. In every case, in colloquial terms, there must, unfortunately, have been something far wrong with the accused, which affected the way he acted.
5. While the plea of diminished responsibility will be available only where the accused's abnormality of mind had substantial effects in relation to his act, there is no requirement that his state of mind should have bordered on insanity.
6. It is for the court to determine, having regard always to relevant policy considerations, whether any particular abnormality can found a plea of diminished responsibility. Thus, no mental abnormality, short of actual insanity, which is brought on by the accused himself taking drink or controlled drugs or sniffing glue, will found a plea of diminished responsibility (Brennan). Similarly, our law does not recognise psychopathic personality disorder as a basis for diminished responsibility (Carraher).
7. If, applying the appropriate tests, the judge concludes that the evidence is not capable of supporting a plea of diminished responsibility, he should direct the jury that, if convicting, they should convict of murder.
8. If, on the other hand, the judge concludes that there is evidence to support the plea, then he must leave it for the jury to consider. In that event the judge's directions to the jury should not simply recite the Savage formula but should be tailored, so far as possible, to the facts of the particular case. The amount of detail required will also depend on the facts of the particular case and on the precise issue in controversy between the Crown and the defence. In essence, the jury should be told that they must be satisfied that, by reason of the abnormality of mind in question, the ability of the accused, as compared with a normal person, to determine or control his actings was substantially impaired.