In the light of the statutory history Mr. Gordon Q.C., for Mr. L, recognised that section 5(1) of the Act of 1959 must have the meaning for which Mr. Pleming contended; but he boldly suggested that section 131(1) of the Act of 1983 should be a given a different meaning, and be restricted to voluntary patients. This submission was primarily based upon certain provisions of the Mental Health (Amendment) Act 1982, which were incorporated in the Act of 1983, a consolidating Act. I trust that I will not be thought to fail to do justice to the skill with which Mr. Gordon formulated and presented his argument if I say that it is, in my opinion, wholly untenable, bearing in mind not only that section 131(1) is in identical terms to section 5(1) of the Act of 1959, but that I have been able to discover no trace, either in the Act of 1982 or in the White Paper of November 1981 which preceded it (Reform of Mental Health Legislation (Cmnd. 8405)), of any intention to depart from, or modify, the recommendations of the Percy Commission upon which section 5(1) was founded, or to amend section 5(1) itself. On the contrary, it was expressly stated in the White Paper (see the Introduction, paragraph 3) that the Act of 1959 had worked well. The main objects of the Bill, as summarised in paragraph 5 of the Introduction, were that the Bill improved safeguards for detained patients, clarified the position of staff looking after them and removed uncertainties in the law. The main improvements, summarised in paragraph 6, had no bearing on the position of informal patients admitted under section 5(1) of the Act of 1959, as was borne out by the succeeding paragraphs of the White Paper and indeed by the Act of 1982 itself.

      I should briefly refer to section 131(2) of the Act of 1983, which was relied on by the Court of Appeal in support of their construction of section 131(1). Subsection (2) reads:

 "(2) In the case of a minor who has attained the age of 16 years and is capable of expressing his own wishes, any such arrangements as are mentioned in subsection (1) above may be made, carried out and determined [even though there are one or more persons who have parental responsibility for him (within the meaning of the Children Act 1989)]."

The words which I have placed in square brackets were substituted by the Children Act 1989. The section in its original form was identical to section 5(2) of the Act of 1959, except that the word "minor" was substituted in 1983 for the word "infant". It is plain, in my opinion, that subsection (2) can have no impact upon the admission of informal patients under subsection (1) which is concerned with patients who consent as well as those who do not object. It is the former category that subsection (2) addresses, with special reference to minors.

      For these reasons, I am unable with all respect to accept the opinion of the Court of Appeal on the crucial question of the meaning of section 131(1). I wish to stress, however, that the statutory history of the subsection, which puts the matter beyond all doubt, appears not to have been drawn to the attention of the Court of Appeal, and that they did not have the benefit, as we have had, of assistance from counsel appearing for the Secretary of State.

      Treatment and care of informal patients

      I turn briefly to the basis upon which a hospital is entitled to treat, and to care for, patients who are admitted as informal patients under section 131(1) but lack the capacity to consent to such treatment or care. It was plainly the statutory intention that such patients would indeed be cared for, and receive such treatment for their condition as might be prescribed for them in their best interests. Moreover the doctors in charge would, of course, owe a duty of care to such a patient in their care. Such treatment and care can, in my opinion, be justified on the basis of the common law doctrine of necessity, as to which see the decision of your Lordships' House in In re F. (Mental Patient: Sterilisation) [1990] 2 A.C. 1. It is not therefore necessary to find such justification in the statute itself, which is silent on the subject. It might, I imagine, be possible to discover an implication in the statute providing similar justification; but even assuming that to be right, it is difficult to imagine that any different result would flow from such a statutory implication. For present purposes, therefore, I think it appropriate to base justification for treatment and care of such patients on the common law doctrine.

      Was the respondent unlawfully "detained"?

      It is against this background that I turn to consider the question whether, as the Court of Appeal held, there has been any unlawful detention of Mr L. in this case. I should record at once my understanding that the question is whether the tort of false imprisonment has been committed against Mr L.; and I do not wish the use of the word "detention" in this context to distract attention from the true nature of the question.

      In the course of their judgment, the Court of Appeal stated (see [1998] 2 W.L.R. 764, 769) that:

 ". . . a person is detained in law if those who have control over the premises in which he is have the intention that he shall not be permitted to leave those premises and have the ability to prevent him from leaving."

I observe however that no mention is here made of the requirement that, for the tort of false imprisonment to be committed, there must in fact be a complete deprivation of, or restraint upon, the plaintiff's liberty. On this the law is clear. As Atkin L.J. said in Meering v. Grahame-White Aviation Co. Ltd (1919) 122 L.T. 44, 54, "any restraint within defined bounds which is a restraint in fact may be an imprisonment." Furthermore, it is well settled that the deprivation of liberty must be actual, rather than potential. Thus in Syed Mahamad Yusuf-ud-Din v. Secretary of State for India (1903) 19 T.L.R. 496, 497, Lord Macnaghten said that: "Nothing short of actual detention and complete loss of freedom would support an action for false imprisonment." And in Meering, at pp. 54-55, Atkin L.J. was careful to draw a distinction between restraint upon the plaintiff's liberty which is conditional upon his seeking to exercise his freedom (which would not amount to false imprisonment), and an actual restraint upon his liberty, as where the defendant decided to restrain the plaintiff within a room and placed a policeman outside the door to stop him leaving (which would amount to false imprisonment). In cases such as the present it is, I consider, important that the courts should have regard to the ingredients of the tort as laid down in the decided cases, and consider whether those ingredients are in fact found to exist on the particular facts of the case in question. With that in mind, I turn to consider the facts of the present case.

      I propose first to consider in detail the circumstances in which Mr L. came to be admitted to hospital. These are described, in particular, in the affidavit sworn in these proceedings on 3 October 1997 by Dr. Manjubhashini, who is the Clinical Director of Learning Disabilities, Deputy Medical Director and Consultant Psychiatrist of Learning Disabilities at the appellant Trust. She describes how Mr L. has been well known to her since 1977. She was the Consultant responsible for his resettlement and trial discharge to Mr. and Mrs E. in 1994. At that time Mr. L. was fairly stable with no major behavioural problems. He was stabilised on medication. In March 1996 the community nurse in regular contact with him reported that there had been an escalation in his self-injurious behaviour; however at a review meeting in June 1996 Dr. Manjubhashini assessed that it was not necessary for him to be readmitted to hospital and that his care should continue in the community if possible. It was on 22 July 1997 that the serious incident occurred which alerted Dr. Manjubhashini and her colleagues to the fact that Mr. L's self- injurious behaviour had increased in severity to such an extent that he required in-patient treatment. At this stage I propose to take the exceptional course of quoting a substantial passage from Dr. Manjubhashini's affidavit:

 "At 11 o'clock on 22 July 1997 I was contacted by Ailsa Flinders, social worker and Mr. L's case manager. She advised me that there had been an incident at Cranstock Day Centre, where Mr. L had been attending since 1995, when Mr. L had seriously self- harmed and was extremely disturbed. She said that he had to be sent to the Accident & Emergency Department and she requested assistance from the psychiatric services to assess Mr. L with a view to admitting him if necessary. One of my team members, Dr. Perera, staff grade psychiatrist, attended the Accident & Emergency Department as requested. His notes state that he took a history from Mary Hendrick who was the team manager at Cranstock Day Centre who reported that since March 1997 Mr. L's episodes of self-injurious behaviour had increased in severity. On 22 July 1997 whilst he was at Cranstock he had been agitated, hyperventilating, pacing up and down and hitting himself on the head with his fists. He was also banging his head on the wall. The whole area had to be evacuated to avoid disturbance and assure the safety of others. He was given 4 mgs of Diazepam to try to calm him down at the time but this had no effect. The G.P. was therefore called who administered 5 mgs of Zimovane. However he still remained agitated in the Accident & Emergency Department. He was assessed and treated at A. & E. Dr. Perera later assessed Mr. L as being agitated and very anxious. He noted redness of both his temples, that he was punching his head with both his fists at times and hyperventilating. Dr. Perera assessed that Mr. L required in-patient treatment and transferred Mr. L to the Behavioural Unit. Dr. Perera noted that Mr. L 'makes no attempt to leave.' I recorded that we considered whether it was necessary to detain Mr. L under the Mental Health Act 1983 ('the Act') but it was decided that this was not necessary as he was, as I noted at the time, 'quite compliant' and had 'not attempted to run away.' He was therefore admitted as an informal patient. If Mr. L had resisted admission I would certainly have detained him under the Act as I was firmly of the view that he required in-patient treatment. This was clearly thought through and supported following discussion with Dr. Perera, Ward Staff, other professionals and Care Services Manager. An appropriate framework of care and treatment was implemented."

Dr. Manjubhashini then described how Mr. and Mrs. E. were informed on 22 July of Mr. L's admission, as was Mr. L's next of kin. At first, with the agreement of Mr. and Mrs E., it was arranged that they would not visit Mr. L for a few days, in accordance with the usual clinical practice. On 23 July Dr. Manjubhashini wrote to the Mr. and Mrs E., and in her letter invited them to come and meet her the following week when it was her intention to discuss the possibility of phased visits, but they did not accept this invitation to meet her. On the same day an advocacy worker was appointed as Mr. L's advocate. Mr. L was again assessed. A programme of tests and observations was then put into effect. Dr. Manjubhashini continued:

 "As Mr. L is an informal patient there has never been any attempt to detain him against his will or carry out any tests, observations or assessments to which he indicated a dislike or with which he refused to co-operate. Mr. L has always accepted his medication which has always been administered orally. He was also fully compliant when blood was taken from him for testing. He did not however co-operate with the attempts that were made to carry out a C.T. scan and E.E.G., which were necessary in view of his old history of fits and temporal lobe abnormality, on the 5 and 6 August 1997 and so these tests were abandoned. Mr. L co-operated to a certain extent with the speech therapy assessment which was carried out on 15 September 1997 and the occupational therapy assessment. However, as soon as he showed any signs of distress the assessments were postponed and reviewed. Mr. L is accomodated on an unlocked ward and has never attempted to leave the hospital but has accepted the change in his environment very well and is not distressed by it . . . It was, in my professional opinion, in Mr. L's best interests to be admitted on 22 July 1997 and it is also in his best interests to continue with in-patient treatment to prevent further deterioration of his mental health. His discharge at this point in time would therefore be against medical advice. At the time of and since admission Mr. L has been fully compliant with treatment and never indicated that he wishes to leave the hospital. In view of this it has not been necessary to detain him under the Act . . . If Mr. L stopped co-operating or indicated a wish to leave then I would have to consider at that time whether his condition warranted detention under Section 3 of the Act. As these circumstances have not so far arisen detention has not been necessary."

      In the light of this account, the following conclusions may be drawn. The first is that, as I have already recorded, although Mr. L had been discharged from hospital into the community on a trial basis, and on that basis had gone to live with Mr. and Mrs. E. as his paid carers, nevertheless he had not been finally discharged. It followed that the appellant trust remained responsible for his treatment, and that it was in discharge of that responsibility that the steps described by Dr. Manjubhashini were taken. The second is that when, on 22 July, Mr. L became agitated and acted violently, an emergency in any event arose which called for intervention, as a matter of necessity, in his best interests and, at least in the initial stages, to avoid danger to others. Plainly it was most appropriate that the appellant trust, and Dr. Manjhubashini in particular, should intervene in these circumstances; certainly Mr. and Mrs E., as Mr. L's carers, could not assert any superior position. Third, I have no doubt that all the steps in fact taken, as described by Dr. Manjubhashini, were in fact taken in the best interests of Mr. L and, in so far as they might otherwise have constituted an invasion of his civil rights, were justified on the basis of the common law doctrine of necessity.

      I wish to add that the latter statement is as true of any restriction upon his freedom of movement as then occurred, as it it is of any touching of his person. There were times during the episode when it might be said that Mr. L was "detained" in the sense that, in the absence of justification, the tort of false imprisonment would have been committed. I have particularly in mind the journey by ambulance from the Day Centre to the Accident and Emergency Unit. But that journey was plainly justified by necessity, as must frequently be so in the case of removal to hospital by ambulance of unfortunate people who have been taken ill or suffered injury and as a result are incapacitated from expressing consent. I wish further to add that I cannot see that Dr. Manjubhashini's statements to the effect that she would if necessary have taken steps compulsorily to detain Mr. L under the Act of 1983 have any impact on the above conclusions. Those concerned with the treatment and care of mentally disordered persons must always have this possibility in mind although, like Dr. Manjubhashini, they will know that this power is only to be exercised in the last resort and they may hope, as in the present case, that it would prove to be unnecessary to exercise it. Such power, if exercised in accordance with the statute, is of course lawful. In the present case all the steps in fact taken by Dr. Manjubhashini were, in my opinion, lawful because justified under the common law doctrine of necessity, and this conclusion is unaffected by her realisation that she might have to invoke the statutory power of detention.

      Finally, the readmission of Mr. L to hospital as an informal patient under section 131(1) of the Act of 1983 could not, in my opinion, constitute the tort of false imprisonment. His readmission, as such, did not constitute a deprivation of his liberty. As Dr. Manjubhashini stated in paragraph 9 of her affidavit, he was not kept in a locked ward after he was admitted. And the fact that she, like any other doctor in a situation such as this, had it in her mind that she might thereafter take steps to detain him compulsorily under the Act, did not give rise to his detention in fact at any earlier date. Furthermore his treatment while in hospital was plainly justified on the basis of the common law doctrine of necessity. It follows that none of these actions constituted any wrong against Mr. L.

      For these reasons, I would allow the appeal.

      Two subsidiary points

      There are however two subsidiary points which I wish to mention, one relating to the judgment of the Court of Appeal, and the other of a more general nature.

      The first is that the Court of Appeal placed reliance on the decision of this House in the Scottish case of B. v. Forsey 1988 S.C.(H.L.) 28 as providing authority for their conclusion. That case was concerned with the invocation of the common law to supplement the statutory power of compulsory detention to fill a lacuna which had appeared in the Scottish Act. This House held that the common law could not be invoked for that purpose, because the powers of detention conferred upon hospital authorities under the Mental Health (Scotland) Act 1984 were intended to be exhaustive. In my opinion, that decision has no relevance in the present case which is concerned with informal admission under the Act of 1983, and bringing a patient to hospital to enable him to have the benefit of such admission if he does not object to it. In this connection, I observe that section 17(2) of the Scottish Act, which is the equivalent to section 131(1) of the Act of 1983, was not referred to in B. v. Forsey.

      The second point relates to the function of the common law doctrine of necessity in justifying actions which might otherwise be tortious, and so has the effect of providing a defence to actions in tort. The importance of this was, I believe, first revealed in the judgments in In re F. (Mental Patient: Sterilisation) [1990] 2 A.C. 1. I wish, however, to express my gratitude to counsel for the appellants, Mr. John Grace Q.C. and Mr. Andrew Grubb, for drawing to our attention three earlier cases in which the doctrine was invoked, viz. Rex v. Coate (1772) Lofft 73, especially at p. 75 per Lord Mansfield; Scott v. Wakem (1862) 3 F. and F. 328, 333, per Bramwell B.; and Symm v. Fraser (1863) 3 F. and F. 859, 883, per Cockburn C.J., all of which provide authority for the proposition that the common law permitted the detention of those who were a danger, or potential danger, to themselves or others, in so far as this was shown to be necessary. I must confess that I was unaware of these authorities though, now that they have been drawn to my attention, I am not surprised that they should exist. The concept of necessity has its role to play in all branches of our law of obligations-- in contract (see the cases on agency of necessity), in tort (see In re F. (Mental Patient: Sterilisation) [1990] 2 A.C. 1), and in restitution (see the sections on necessity in the standard books on the subject)--and in our criminal law. It is therefore a concept of great importance. It is perhaps surprising, however, that the signifcant role it has to play in the law of torts has come to be recognised at so late a stage in the development of our law.

LORD LLOYD OF BERWICK

My Lords,

      I have had the advantage of reading in draft the speech prepared by my noble and learned friend, Lord Goff of Chieveley. For the reasons he gives I too would allow the appeal.