Implied terms

Implied terms are commonly divided into terms implied in fact and terms implied in law. What are they and when will they arise?

Terms implied in fact

The original test for when the courts would imply a term in fact into a contract was laid down in 1889 in The Moorcock (where it was argued, and accepted, that there was a term implied in a contract for mooring a ship at the jetty under which the defendant owners of the jetty guaranteed that they had taken reasonable steps to see that the depth of the water around the jetty was such that it was safe for the claimant shipowners to moor their ship at the jetty). This was the business efficacy test: ‘what the law desires to effect by the implication is to give such business efficacy to the transaction as must have been intended at all events by both parties who are business men’ (per Bowen LJ). So under the business efficacy test the courts will imply a term in fact into a contract where it was necessary to do so to make the contract work in the way that was intended by the parties to the contract.

A different test was suggested by MacKinnon LJ in the 1939 case of Shirlaw v Southern Foundries (1926) Ltd (where it was argued, and accepted, that there was an implied term in a contract appointing a managing director of a company for ten years that the company would not remove the director from his position for the period of his appointment, and it would not alter its articles of association so as to enable the director to be removed). This was the officious bystander test: ‘Prima facie that which in any contract is left to be implied and need not be expressed is something so obvious that it goes without saying; so that, if, while the parties were making their bargain, an officious bystander were to suggest some express provision for it in their agreement, they would testily suppress him with a common “Oh, of course!”’

There are problems with both these tests. Consider:

Dodgy: A Finance company sells an investment product to Mug knowing that the product is worthless and that Mug will probably lose a lot of money on the deal. However, selling the product to Mug (and thousands like him) will help Finance avoid the consequences of some terrible investment decisions that it made in the past. Mug has now lost a lot of money as a result of owning this investment product and wishes to sue Finance, arguing that there was an implied term in the contract of sale that Finance would warn the claimant if it knew that the product it was selling him was worthless.

Secretary: Randy appoints Beauty to work for him as a secretary. Randy has always fancied Beauty; in fact, that is the main reason why Beauty got the job. Two days after starting work, Randy tells Beauty he can’t stop thinking about her and would like them both to go away for a naughty weekend in Blackpool. Beauty does not welcome Randy’s advances and wants to argue that there is an implied term in her contract with Randy that Randy will not ask her out or in any way indicate that he is sexually attracted to her.

Neither of these terms need to be implied into the contracts in Dodgy and Secretary respectively in ordert to make the contracts work. Implying a term that Finance will warn Mug if it knows the product it is selling him is worthless will actually negate the contract, as Mug will not contract with Finance if he is given such a warning. And Beauty does not really need Randy to shut up about how much he fancies her to get on with her job of working for him as a secretary. So neither of these terms could be implied under the business efficacy test. And if we apply the officious bystander test, it is obvious that had an officious bystander asked Mug and Finance, ‘Is Finance undertaking to warn Mug if it knows this product is worthless?’ then Mug would probably have said ‘Of course!’ but Finance would have said ‘No, we’re not – it’s for Mug to decide whether or not to buy this product.’ And if an officious bystander had asked Randy and Beauty, ‘Is Randy undertaking not to sexually harass Beauty?’ then Beauty would probably have said, ‘Of course!’ but Randy would have said, ‘I think that’s a bit extreme – if I want to tell Beauty how beautiful she is, I think I should be allowed to do that.’

Maybe we should rest content with that, and say that Mug and Beauty will lose their cases, insofar as they are based on the implication of a term in fact into their contracts with Finance and Randy respectively. However, Mug and Beauty may still have two arguments left to them when arguing that there was an implied term in fact in their contracts:

(1) The Belize argument

In Attorney General of Belize v Belize Telecom Ltd (2009) (where it was argued, and accepted, that there was an implied term in a company’s articles of association that a director who had been appointed under a special procedure that could only be invoked by a shareholder holding a ‘golden’ share in the company and over 37.5% of ‘C’ shares in the company should step down if the shareholder who had appointed him subsequently sold some of its ‘C’ shares so that it no longer held 37.5% of the ‘C’ shares in the company), Lord Hoffmann suggested that both the ‘business efficacy’ and ‘officious bystander’ tests for implying a term in fact into a contract should be superseded by a new test under which a term will be implied into a contract if such a term ‘would spell out in express words what the [contract], read against the relevant background, would reasonably be understood to mean’ (at [21]).

As John McCaughran (‘Implied terms: the journey of the man on the Clapham omnibus’ (2011) 70 CLJ 607, at 614) has acutely pointed out, this test for implying a term in fact into a contract involves applying a reverse ‘officious bystander’ test – instead of the officious bystander asking the parties what they have meant to agree, the parties ask the bystander ‘You know the business background against which we are dealing – what do you think we have agreed in entering into this contract?’ Taking the power to determine the terms of the contract out of the hands of the parties and into the hands of a reasonable bystander might make it easier for Mug and Beauty to win their cases.

However, Hoffmann’s test for implying a term in fact into a contract can be criticised on a number of grounds. (i) He uses the exact same test for interpreting the terms of a contract (see his decision in Investors Compensation Scheme Ltd v West Bromwich Building Society (1997)) as he does for implying terms into a contract, but as Bingham MR pointed out in Phillips Electronique Grand Public SA v British Sky Broadcasting (1995), the two things are very different exercises – implying a term in a contract that the parties did not expressly say they wanted to be part of the contract is a lot more of an intrusion on the parties’ freedom of contract than trying to determine what the parties meant by a term that they did expressly say that they wanted to be part of the contract. (ii) Hoffmann’s test makes it too easy for the courts to impose on the parties to a contract terms that they did not want to be part of the contract, on the basis that a reasonable person with a similar business background to the parties would have thought that that term was part of the contract. (iii) Hoffmann’s test is also very vague and creates a great deal of commercial uncertainty for parties entering into contracts, as they would find it hard to predict what terms a court employing Hoffmann’s test might end up implying into the contract.

Perhaps significantly, the caselaw since the Belize case has not expressed much enthusiasm for Hoffmann’s test, with (1) the CA in Mediterranean Salvage & Towage v Seamar Trading & Commerce Inc (2009) endorsing the ‘business efficacy’ test, (2) the CA in Groveholt Ltd v Alan Hughes (2010) endorsing the ‘officious bystander’ test, and (3) a majority of the UKSC effectively disowning the test in Marks & Spencer plc BNP Paribas Securities Services (2015) (at paras [22]-[31], per Lord Neuberger, with Lord Carnwath supporting the Hoffmann test in his judgment) in favour of implying a term when the ‘business efficacy’ test or the ‘officious bystander’ test indicates such a term should be implied (para [21], per Lord Neuberger). (See elsewhere on this website for a detailed casenote on the Marks & Spencer case.) So it is doubtful whether we should seek to rely on Hoffmann’s test in Mug and Beauty’s cases.

(2) The officious bystander argument revisited

Both Mug and Beauty might be able to argue that the ‘officious bystander’ test is satisfied in their cases. Both would rely on the fact that had an officious bystander asked whether Finance was promising to warn Mug if it knew that it was selling him a worthless product, or whether Randy was guaranteeing that he would not sexually harass Beauty, while Finance and Randy might say now that they would not have gone along with the officious bystander’s suggestion, at the time the contract was entered into things would have been very different. The officious bystander’s question would have put Finance and Randy in a very difficult position: they would either have had to confess that, no, they wanted the option of selling Mug or worthless product or sexually harassing Beauty and endanger the deal, or they would have had to act as though they were decent people and say to the officious bystander, ‘Of course we would never sell Mug a product that we knew to be worthless’ or ‘Of course I would never dream of making sexual advances to Beauty.’ Faced with this choice, they probably would have done the latter and suppressed the officious bystander with a testy, though grudging, ‘Oh, of course!’. Given this, Mug and Beauty might be able to argue that the officious bystander test is satisfied in their cases, or at least that Finance and Randy should not be allowed now to argue that the officious bystander test is not satisfied, given that at the time they would have probably been embarrassed (for fear of looking like a really dodgy person) or forced (for fear of endangering the deal) into giving a positive response to the officious bystander’s question.

I think argument (2) would probably work (see, in particular, para [21] of Lord Neuberger’s judgment in the Marks & Spencer case: ‘If one [asks] what the parties would have agreed, one is not strictly concerned with the hypothetical answer of the actual parties, but with that of notional reasonable people in the position of the parties at the time at which they were contracting’), and indicates that the officious bystander test, if sensitively applied, copes well with difficult cases such as Dodgy and Secretary. But less can be said in favour of the business efficacy test – if it would rule out an implied term in cases like Dodgy and Secretary on the ground that the terms were not needed to make the contract work, when such terms would be implied on the officious bystander test, then that seems to indicate that officious bystander test provides a more comprehensive test for implying a term in fact into a contract than the business efficacy test does.

Terms implied in law

It follows from the above that terms implied in fact into a contract are designed to give effect to the intentions of the parties – or what the parties reasonably indicated that they intended – in entering into the contract. Terms implied in law are quite different. Terms implied in law act as default rules for particular, well-established types of contractual relationship, such as those that exist between a business seller of goods and a purchaser of those goods, an employer and an employee, an insurance company and someone purchasing insurance from that company, a shipowner and an owner of goods placed aboard the ship, a builder and a client, a landlord and a tenant, and so on and so on. A default rule is a rule that will apply to a particular relationship unless the parties to that relationship indicate that they don’t want it to apply. Default rules are a huge aid to efficiency in contracting: they allow the parties to a well-established type of contractual relationship to contract with each other safe in the knowledge that a large number of terms will automatically be implied into the contract to safeguard their respective interests and that all they need to focus on in their negotiations are a few terms which need to be fiddled with to fit the circumstances of their case. (In the same way, the fact that when you open a new document on your computer, the fact that document is preformatted according to certain default rules for page size, font, margins, line spacing and so on, means they you can get on with writing what you want to write much more quickly: you don’t specify every aspect of what your document should look like – you can just focus on adjusting particular default rules that you don’t want to apply.)

Once we understand the status of terms implied in law as default rules, two things follow:

(1) We can make sense of the emphasis that the House of Lords placed in Liverpool City Council v Irwin (1977) on the courts’ only implying a term by law into a contract when it is necessary to do so. ‘Necessary’ here does not mean the same as ‘necessary to give business efficacy’ to the contract. If it did, then the House of Lords’ decision in Irwin would have effectively abolished terms implied in law. But it did not: the term that the House of Lords ended up implying in Irwin into the contract in that case between the landlord (the city council) and its tenants occupying a block of flats known as ‘the Piggeries’ was a term requiring the landlord to take reasonable steps to keep the common parts of the let premises in good repair. (In this case, that would have been the lifts and the stairs.) The House of Lords did not need to imply that term into the contract between the landlord and the council tenants in order to make the contract work properly – so ‘necessary’ in Irwin could not have meant ‘necessary to give business efficacy’ to the contract. What the House of Lords actually meant (see, on this, Jane Stapleton, ‘Duty of care and economic loss: a wider agenda’ (1991) 107 LQR 249, 290-1) by ‘necessary’ in this context was ‘The suggested term has to be such that we think it would be reasonable to imply this into any contract of the general type with which this case is concerned, so that from now on that term would become (unless the parties indicated otherwise) a necessary incident of a contract of that type.’ So before the House of Lords could imply a term by law into the landlord-tenant contract in Irwin, requiring the landlord in that case to take reasonable care of the common parts of the let premises, the House of Lords had to be convinced that it would be reasonable to imply such a term into any landlord-tenant contract no matter who the landlord might be and who the tenant might be. And plainly it was reasonable: when you are letting premises to a large number of people, it seems obvious that the responsibility for looking after the common parts of the premises should fall on the landlord and it would be very difficult for the tenants to co-ordinate efforts themselves to keep those common parts in good repair.

(2) When you are doing a problem question which turns on whether you can imply a term into a particular contract, and you have found that no such term can be implied in fact into the contract, it would be unwise to confidently assert that the courts will imply such a term in law into the contract unless you have statute or caselaw to support that assertion. If you do not, and it is a novel question whether the courts would imply a term in law of the type you are considering into this kind of contract, you cannot have any confidence that the courts will imply such a term into a contract, given the huge number of factors the courts would have to take into account in determining whether it would be reasonable to imply such a term into all contracts of that type. (For an account of these considerations see Peden, ‘Policy concerns behind implications of terms in law’ (2001) 117 LQR 459.) So when you are considering whether the courts will find that a term was implied by law into a particular type of contract, stick closely to the existing caselaw and statute law on this issue. And when it comes to the existing law, the two most important terms that will be implied by law into a contract (unless the parties indicate that they do not want the term to be implied – and even then their freedom to avoid that term may be limited by the Unfair Contract Terms Act 1977) that you have to know about and carry around with you in your mental knapsack are: (i) the terms implied into a contract between a business seller of goods and someone buying those goods that the goods will be of satisfactory quality and reasonably fit for the purpose for which the buyer let the seller know he wanted the goods (under s 14 of the Sale of Goods Act 1979); and (ii) the term implied into a contract for the supply of services, supplied in the course of business, that those services will be performed with a reasonable degree of care and skill (under s 13 of the Sale and Supply of Goods and Services Act 1982). Implied term (ii) is particularly useful as it applies in a wide range of circumstances – builder-client contracts; hotel-guest contracts, cinema-customer contracts, restaurant-diner contracts, and so on and so on.

Why actions matter to the criminal law

Compare the following two cases:

Poison: Patient is terminally ill and is in a lot of pain that cannot be relieved through palliative measures. In order to bring his suffering to an end, Doctor injects Patient with some poison and Patient dies.

Dehydration: Patient is terminally ill and is in a lot of pain that cannot be relieved through palliative measures. Doctor orders that Patient should not be given any more food and water, and Patient dies of dehydration.

In Poison, Doctor commits murder. In Dehydration, Doctor does not commit any crime at all. But the only difference between these two cases is that Doctor has performed an act in Poison whereas all he is guilty of in Dehydration is an omission. Doctor could only be held liable for his omission in Dehydration if he had a duty to continue feeding Patient and giving him water; but he would have had no such duty if there was no point in continuing to treat Patient and giving Patient food and water is regarded as part of Patient’s ‘treatment’ (as it was in Airedale NHS Trust v Bland). In contrast, Doctor will always be under a duty not to take positive steps to bring Patient’s life to an end.

But we can’t just rest content with saying that Doctor is held liable in Poison while he is held blameless in Deyhydration because he breached a duty in Poison while he did not in Dehydration. That just raises the question of why there is a duty not to act in Poison when there is no duty to act in Dehydration. Why is what Doctor did in Poison so much worse than what he failed to do in Dehydration that the law will say that there was a duty not to act in Poison while there was no duty to act in Dehydration? After all, if we are just looking at the consequences of what Doctor did, Doctor’s actions in Poison look a lot better than Doctor’s omissions in Dehydration. In Poison, Doctor brought Patient’s suffering to a quick and painless end. In Dehydration, Doctor condemned Patient to a very difficult, agonising and prolonged death (though doing so may still have been in Patient’s ‘best interests’ given the alternative of allowing Patient to continue to suffer weeks or even months of extreme pain before the final end).

Some would argue, on this basis, that (to quote Lord Mustill in Bland) the law is ‘both morally and intellectually misshapen’ in distinguishing between Poison and Dehydration and that we should not find Doctor guilty of murder in Poison. Others (see, for example, Finnis, ‘Bland: crossing the Rubicon?’ (1993) 109 LQR 329) would agree with the premise of this argument but disagree with the conclusion: they would argue that we can only restore order to this area of the law by overruling Bland and holding that Doctor is just as much guilty of murder in Dehydration as he is in Poison: giving a patient food and water should not be regarded as being part of a patient’s ‘medical treatment’ and even if there is no further point in giving the patient medical treatment, there is still a duty to give the patient food and water so long as the patient is able to ingest it. So a breach of that duty that brings about death, when accompanied with an intent to kill, should be regarded as murder.

From a religious point of view, it is easy to see why we might distinguish between Poison and Dehydration. In Poison, Doctor is intervening to alter the natural course of events that would otherwise determine when Patient dies – which is not allowed if you think that that natural course of events represents God’s will for when Patient should die. In contrast, in Dehydration, Patient dies of natural causes – if you don’t get water for long enough, you die. And while we could argue about whether Doctor violated God’s will in withholding food and water from Patient – with the result that, from a religious perspective, his failure to act in Dehydration is just as bad as his act in Poison – the fact that Poison represents a much more obvious case of ‘playing God’ than Dehydration may be enough to justify our drawing a distinction between the two cases.

However, in a secular society, religious arguments for distinguishing between Poison and Dehydration are out of bounds. Can we find a non-religious basis for distinguishing between these two cases? The normal secular arguments for why the law should draw distinctions between acts and omissions – that if the law is too ready to find duties to act this will (1) undermine civil liberties; (2) create a great deal of uncertainty in the law; (3) deprive people of opportunities to earn credit from others for doing the right thing when they weren’t compelled to do so; (4) ‘punish’ people for putting themselves in positions to help others in need by subjecting them to legal duties that people who have made more selfish choices will never incur – don’t seem to apply here to distinguish Poison from Dehydration. If the law said there were a duty to act in Dehydration, doing so wouldn’t seem to have any of the undesirable effects that would normally accompany the law’s finding that one stranger owed another stranger a duty to save him or her from harm. However, it may be that we can make a ‘civil liberties’ argument in favour of the law’s finding that Doctor had a duty not to act in Poison when it says that he did not have a duty to act in Dehydration.

The argument goes as follows: if the law finds that it was permissible for Doctor to kill Patient in Poison, then it will not be long before the law finds that it was compulsory for Doctor to kill Patient in Poison. This is because the law gives doctors very little leeway in treating their patients – either the doctor had a duty to administer a particular treatment, or he had a duty not to administer that treatment: the law rarely (never?) says to a doctor ‘It’s entirely up to you whether or not to you administer that treatment.’ So if the law said it was permissible for Doctor to kill Patient in Poison then it’s hard to see how it could not then make the further leap of saying that it was compulsory for Doctor to kill Patient in Poison. But saying this would involve a very serious interference with Doctor’s civil liberties: many doctors do not want (for whatever reason) to kill their patients, and would seriously resent the law’s compelling them to kill their patients. And if doctoring were seen as coming with a duty to kill in certain circumstances, then the number of people wanting to become doctors would radically diminish. The same problem does not arise in relation to the law’s saying that Doctor has no duty to feed or water Patient in Dehydration. If the law follows that up by saying that it is compulsory for Doctor not to give Patient any food or water in Dehydration, most doctors would be able to be reconciled with that. The fact that the law might get in the way of a doctor acting on her normal instinct to give a patient food or water – even if nothing more can be done for the patient – would not be experienced by the doctor as a violation of her civil liberties any more than the fact that the size or location of her hospital places a limit on how many patients she can treat, or her need to respect her patient’s wishes places a limit on what she can do for that patient. The state of the law would just be one more fact which places a limit on how much she can do for the patients she would otherwise wish to treat, and which she just has to learn to live with.

Tort Law Casenotes

Click on the links below to access casenotes on a variety of tort law cases (for many more casenotes, click on the links to the McBride and Bagshaw Tort Law Companion Website above):

Vicarious Liability Cases

Economic Torts Cases

Dunnage v Randall

International Energy Group Ltd v Zurich Insurance plc UK

Michael v Chief Constable of South Wales Police

Montgomery v Lanarkshire Health Board

O v Rhodes

Patel v Mirza

Willers v Gubay

Williams v Bermuda Hospitals Board

Flood v Times Newspapers Ltd

Mitchell v Glasgow City Council

Smith v Ministry of Defence

Van Colle v Chief Constable of Hertfordshire Police

Trent Strategic Health Authority v Jain

Woodland v Swimming Teachers Association

Yearworth v North Bristol NHS Trust

The defence of insanity

The cases of Anders Breivik (who shot 69 people on Utoya Island in Norway) and James Holmes (who shot 12 people in a cinema in Aurora, Colorado) raise again the issue of when a criminal defendant should be able to take advantage of a defence of insanity. As laid down in the M’Naghten Rules (‘MR’, for short), the defence of insanity will be available to a defendant if, at the time he acted, he was ‘labouring under such a defect of reason, from a disease of the mind, as not to know the nature and quality of the act he was doing; or if he did know it, that he did not know what he was doing was wrong.’

One criticism that it is often made of the defence of insanity is that it is medically outdated – that our notions of when someone can be said to have been medically insane in acting as he did have developed since 1843, when the MR were laid down, and the law has failed to keep pace with those developments. However, this criticism is unjustified: in my view, the MR are not intended at all to reflect clinical or medical ideas as to when someone should be said to be insane.

Instead, I think the MR are directed at identifying cases where: (1) it was impossible for the defendant to alter his conduct to make it conform to the law (which accounts for the requirement that the defendant must not have known what he was doing or must not have known that what he was doing was wrong), and (2) the defendant was unable to alter his conduct to make it conform to the law because he suffered from an internal condition which means that the defendant is likely to do what he did again, and therefore constitutes a public danger that needs to be dealt with (which accounts for the requirement that the defendant’s incapacity arises out of a ‘disease of the mind’).

On this view, then, the MR are not at all concerned to reflect modern medical notions of when someone can be said to be insane: they arise out of a dual concern to uphold the requirements of the rule of law – which would dictate that someone not be held liable for breaking the law if he was incapable of being guided by its dictates – and to ensure that people who get the treatment they need to deal with conditions that they have that, if unaddressed, will prevent them from complying with the law in the future.

So it really does not matter whether Breivik or Holmes were medically insane when they acted as they did (which they probably were). They were both clearly capable of conforming their conduct to the law, and as such can be properly held accountable for their failures to exercise that capacity. If – having been imprisoned for their crimes – they also require medical treatment to deal with their psychiatric conditions (as Peter Sutcliffe, the Yorkshire Ripper, did, eventually being incarcerated in Broadmoor Hospital under the Mental Health Act 1983) then they should receive it; but their psychiatric states cannot excuse them from being punished for their failures to obey the law.

All of this is not to say that the law on when someone will be found not guilty by reason of insanity is perfect. Four criticisms of the law can be made.

(1) Stigma. There is a concern that defendants who fall within the MR might be put off pleading that they are ‘not guilty by reason of insanity’ because of the stigma attached to being labelled as ‘insane’. This concern gets particularly strong in cases like Sullivan (epilepsy) and Hennessy (diabetes) where what triggered the defendant’s incapacity to comply with the law was an internal condition that no one would ordinarily categorise as ‘insanity’. If the MR are really not concerned with medical notions of insanity, there is a case for saying that we should not use the term ‘insanity’ to refer to the defence to which the MR apply. However, it is difficult to think of what alternative name we could give this alternative defence. ‘Not guilty by reason of internal incapacity’ feels a bit too clinical.

(2) Civil liberties. Another reason why defendants might be unwilling to plead ‘not guilty by reason of insanity’ is that if the plea is successful, then the court is then empowered under s 3 of the Criminal Procedure (Insanity and Unfitness to Plead) Act 1991 to make an order requiring the defendant to be restrained in hospital for an ‘unlimited period of time’. Now – the court does not have to make such an order (though it does in the case where the sentence for the offence which the defendant was charged with is fixed by law (effectively, murder cases)) – it could make a more limited order, or even an absolute discharge. But the possibility that a court might make such an order in their case would make a defendant – particularly one who is charged with a relatively petty offence such as shoplifting – hesitate long and hard before making a plea of ‘not guilty by reason of insanity’ for fear of being trapped in a One Flew Over the Cuckoo’s Nest situation of being trapped in an institution where you are not insane, but are treated as though you are, and are eventually driven crazy by the experience. One way of getting round this problem would be to amend the 1991 Act to require a defendant who has been committed to hospital having pleaded ‘not guilty by reason of insanity’ to appear before a judge at regular intervals so that the judge (preferably the one who presided over the defendant’s trial) can evaluate their treatment and condition and ensure that they are not being treated inappropriately.

(3) Falling between two stools? The defence of ‘not guilty by reason of insanity’ exists alongside the ‘defence’ of non-insane automatism – which is not really a defence, but a denial that the defendant committed the actus reus of the crime because an external cause (for which the defendant was not at fault) meant that the defendant was unaware of what he was doing (the defendant ‘blacked out’) or was aware of what he was doing, but was unable to control his bodily movements (the defendant was acting reflexively). However, there may be one situation which falls between these two defences, because it does not come under either of them. This is the situation where due to an external cause (for which the defendant was not at fault) the defendant thinks that there is nothing wrong – either legally or morally – with acting in a particular way, and he goes on to act in that way, where acting in that way amounts to the actus reus of an offence. For example: D is hit on the head by a stone. When he comes to, he thinks that he is the emperor of the world, and that all women are required to have sex with him, if he so wishes. He proceeds to have sex with V against her will. D won’t be able to rely on a defence of non-insane automatism because he was not acting as an automaton in having sex with V – he knew what he was doing, and was in control of his body. But will he be able to take advantage of a defence of ‘not guilty by reason of insanity’? The difficulty is that his delusions were triggered by an external cause – that of being hit on the head by a rock. Perhaps it could be argued that the external cause triggered a ‘disease of the mind’ and in that way allow him to take advantage of the defence of insanity. But this seems hard to reconcile with cases like Bailey, where the defendant acted under the influence of an insulin injection, and was held not to be able to take advantage of the defence of insanity. (Though it looks like the defendant knew what he was doing in that case – though he might not have been aware of the effects of his actions.)

(4) Strict liability. In DPP v Harper, the Court of Appeal ruled that the defence of insanity did not apply to strict liability offences – in that case, driving with excess alcohol in one’s bloodstream. This seems wrong. If the MR are directed at someone’s being unable to conform their conduct to the law, then there seems no reason why they should not apply as much to strict liability offences as they do to offences which require some degree of mens rea for their commission. A defendant who seeks to take advantage of the MR is not denying that he had the mens rea for the offence with which he is charged: he is making a much more basic point – that he should not be held responsible for his actions because they were either not his actions or they were performed in ignorance of the fact that they might be contrary to the law (and he was not at fault for that ignorance – so the maxim ignorantia legis non excusat does not apply). (Having said that, there are a couple of cases which suggest that a strict liability offence will capture someone who was completely incapable of avoiding committing that offence, and on that basis they refused to find that the offence in question was a strict liability offence. They are Sherras v De Rutzen (refusing to find that the offence of selling alcohol to an on-duty policeman was a strict liability offence as it would be impossible for someone selling alcohol to know whether a policeman was on-duty or off) and Lim Chin Aik v R (refusing to find that the offence of entering Singapore when having been prohibited from doing so was a strict liability offence as the notices prohibiting someone from entering Singapore were only published in Singapore, and so it would be impossible for someone outside Singapore to know whether they were prohibited from entering Singapore). These cases may be confusing absolute liability – where it is no defence to say ‘It was impossible for me to avoid the prohibited conduct’ – and strict liability, where in principle it should be a defence to say that it was impossible to avoid doing the thing which is prohibited.)