Introduction This chapter considers, in general terms, the elements of an offence which the prosecution must establish, beyond reasonable doubt, before a person can be convicted. Before you go any further please listen to audio presentation 2 which you can access from the criminal law page of the VLE. It is important that you do so as it will give you an overview of the topic and guidance on the terms considered in this chapter (i. e. actus reus and mens rea). You will now be aware that every offence is defined somewhere – either in a statute or at common law – and will be composed of a number of elements with which you should be familiar.
Note that you should be equally familiar with the elements of each defence you consider as part of this course. The elements of an offence are the external elements (actus reus) and the internal – or mental – elements of the offence (mens rea) which are contained in the definition of that offence (which will be found either at common law or in a statute). The offence of criminal damage contrary to s. 1(1) of the Criminal Damage Act 1971 is used to exemplify analysis of the actus reus and the mens rea of a criminal offence.
Chapters 3 to 6 examine the general principles of actus reus and mens rea in more detail. Essential reading and listening ? Wilson, Chapter 4: ‘Actus reus’, Sections 4. 1–4. 4 and Chapter 6: ‘Mens rea’, Sections 6. 1–6. 5. Audio presentation 2. ? Learning outcomes By the end of this chapter and the relevant readings you should be able to: ? ? find the definition of a criminal offence demonstrate an understanding of the constituent elements of that definition, i. e. actus reus and mens rea demonstrate an awareness of the limits of the terms actus reus and mens rea when used without further clarification.
? Criminal law Chapter 2 The elements of an offence page 13 2. 1 General analysis of criminal offences Every criminal offence is made up of a number of elements, each of which must be proved beyond reasonable doubt before a defendant can be convicted of the offence with which he or she has been charged. A criminal offence might be a statutory offence, such as theft contrary to s. 1 of the Theft Act 1968, or it might be an offence at common law. Most offences are now statutory but a few – including murder and manslaughter (see Chapters 7 and 8) – remain offences at common law.
Traditionally criminal offences are analysed by reference to the actus reus and the mens rea. The Latin maxim actus non facit reum, nisi mens sit rea means that the act itself does not constitute guilt unless it was done with a guilty mind. Another way of saying this is that criminal liability requires BOTH wrongdoing and culpability or blameworthiness. This is, in fact, not a completely accurate description of the criminal law as many crimes do not require mens rea, i. e. blameworthiness. Where mens rea is not required liability is termed ‘strict’. Actus reus
This is the ‘external’ element of a crime – i. e. some form of measurable wrongdoing. It comprises the actor’s conduct, together with any circumstances which make that conduct wrongful, and, in the case of a result crime, the consequences. Mens rea This is the ‘internal’ or mental element of a crime. It must be proved that at the time the defendant was responsible for the actus reus of the offence with which he is charged, he behaved with the state of mind relevant to that offence. So to be guilty of theft he must be proved to be dishonest and intend to keep the property.
Where the offence is one which requires proof of mens rea, both elements (i. e. actus reus and mens rea) must be proved in order to secure a conviction. Furthermore, it must be proved that the mens rea coincided with the actus reus (see Chapter 6). Note that even if a defendant committed the actus reus of the offence with the appropriate mens rea he or she may be able to raise a defence which would negate any criminal liability. Activity 2. 1 Read Glanville Williams, Textbook of criminal law, 2nd edition pp. 70–74, which you will find in your study pack and consider the following questions.
(Note that the definition of rape on p. 72 has changed since this book was written – see s. 1 of the Sexual Offences Act 2003 – but the general point he makes remains valid. ) a. Why is a driver who accidentally runs over and kills a pedestrian not guilty of murder? b. What factors would make this murder? Self-reflection Can you think of any examples where a person’s conduct might not be considered immoral under the circumstances but it would, nevertheless, be criminal? Are there any types of conduct commonly considered to be immoral which you would like to see made criminal?
Now let us look at the definitional elements of the offence of theft contrary to s. 1(1) of the Theft Act 1968. Go to your statute book and find this statute. Alternatively, go to www. legislation. gov. uk/ukpga/1968/60 where you will find it. You will see that a person is guilty of theft if he ‘dishonestly appropriates property belonging to another with the intention of permanently depriving the other of it’ (s. 1(1) Theft Act 1968). page 14 University of London International Programmes Activity 2. 2 Consider the following scenarios.
Bearing in mind that every element of an offence must be proved in order to convict, do you think that the parties below are guilty of theft? Use the wording of s. 1 to guide you. This exercise requires you to consider both the actus reus (Chapters 3 and 4) and the mens rea (Chapter 5) of the offence. a. Susan was in her local supermarket. After checking that nobody was looking, she picked up a bar of chocolate and ate it. b. John grabbed Ann’s purse and ran away with it intending to take the money out of it and then throw the purse away.
Ann’s friend, Anton, who saw what had happened, chased after John and caught him before he could take the money. Anton returned Ann’s purse to her. c. Beth and Amy were in the library. Beth asked Amy if she could borrow her copy of Wilson for 10 minutes. Amy said ‘No’. Amy then went off for a coffee leaving her Wilson on the desk. Beth took the book, intending to return it before Amy returned. Unfortunately, before she could do so, Amy came back and was very angry with Beth for taking her book. d. John took an umbrella believing it to belong to Fred.
Unknown to John it was his own umbrella. Activity 2. 3 a. Find the definitions of the following offences:† i. Murder ii. Wounding with intent to cause grievous bodily harm iii. Robbery iv. Fraud. b. What are the actus reus and mens rea of each of these offences? Tip. The mens rea is what is left over when you have subtracted the actus reus from the definition. There is no feedback for this activity. † Use the index and the list of statutes in Wilson. 2. 2 Limitations on the value of the Latin terms actus reus and mens rea A word of warning.
The terms ‘actus reus’ and ‘mens rea’ are terms of art† which, when used on their own and without explanation, provide no sensible information. Similarly if, having considered a scenario in which, say, A shot B killing him, you simply said, ‘The actus reus is established’, a reasonable response might be: ‘The actus reus of what offence? ’ You might then respond: ‘The actus reus of murder. ’ Although this may be correct it is still less than informative as you have not explained what the ingredients of the actus reus of murder are and why the facts indicate that it was made out.
Therefore it would be correct to say that, in order to establish the actus reus of murder, the prosecution must prove that A unlawfully killed a human being (murder is considered in Chapters 7 and 8). Nevertheless, these are the conventional terms which will be used in all the criminal law materials you are likely to read – including this subject guide. When you use these terms ensure that you use them appropriately. † A ‘term of art’ is a technical term which has a special significance. Self-reflection Return to Activity 2.
3 and look again at the actus reus and mens rea for theft and each offence listed. Now compare them and you will see, on the whole, how different they are. (It might help to write them down. ) For example, the actus reus of theft is entirely different from the actus reus of murder. In addition, although Criminal law Chapter 2 The elements of an offence the mens rea for each of these offences is expressed as ‘intention’, you can see that proof of an intention to achieve entirely different results is required depending upon which offence is charged.
Always express this in any answer you give to activities or questions in the examination. You might also have noted that, where the mens rea for murder is intention to kill or cause grievous bodily harm, the mens rea requirement for the offence contrary to s. 18 of the Offences Against the Person Act is intention to cause grievous bodily harm. It follows from this that, if a person attacks another causing them grievous bodily harm, having intended to do so, they will be guilty of the s. 18 offence. If, however, the victim of the attack dies the attacker will be guilty of murder – subject to any defences he or she may have.
For most of the offences we will be dealing with in this subject guide, it will be necessary for the prosecution to prove both the actus reus and the mens rea of the particular offence. However, for some offences liability is strict. This means that neither the definition of the offence imports a requirement of mens rea as to at least one of the elements of the actus reus, nor has the offence been interpreted by the courts as requiring proof of mens rea in respect of that element. See Chapter 6. page 15 Activity 2. 4 a. Where are the definitions of offences to be found?
b. What is meant by the Latin maxim actus non facit reum, nisi mens sit rea? c. Read Sections 4. 1–4. 2 in Chapter 4 and Section 14. 2 in Chapter 14 of Wilson. What are the conduct and circumstances elements of the actus reus of the offence of theft? d. What is the consequences element of the actus reus of the offence of murder? e. Read the article by Nigel Hanson in your study pack. Why did David Ibbetson, Professor of Civil Law at Cambridge University, have reservations about modernising legal language? 2. 3 Proof of the ingredients of an offence.
The burden is on the prosecution to prove beyond reasonable doubt all of the elements of an offence with which a defendant is charged (see Woolmington v DPP  AC 462). It follows therefore that, whether the offence is one of strict liability or one which requires proof of mens rea, if all of the elements of the actus reus cannot be proved the defendant cannot be criminally liable, however guilty his mind is. † Activity 2. 5 Read Section 4. 3 in Chapter 4 of Wilson. ? Mens rea and strict liability offences are considered in Chapter 5. †.
Can Dadson (1850) 2 Den 35 be reconciled with Case 6? There is no feedback for this activity as the answers are to be found within the passage in Wilson. Now let us consider s. 1(1) of the Criminal Damage Act 1971, which defines the offence of criminal damage as occurring where a person: … without lawful excuse destroys or damages any property belonging to another intending to destroy or damage such property or being reckless as to whether any such property would be destroyed or damaged… It will be clear that the actus reus of this offence (i. e.the external element of the offence) will be established where a person ‘destroys or damages any property belonging to another’.
† If we analyse this external element further it will also be clear that the ‘conduct’ element of the actus reus of criminal damage is any conduct which results in the damage to or destruction of the property and this would include an omission to act (see Chapter 3). † As to whether the requirement ‘without lawful excuse’ is an element of the offence or a defence is discussed below. page 16 University of London International Programmes.
The ‘circumstances’ element of the actus reus of criminal damage will be satisfied by proof that what was destroyed or damaged was property which belonged to another and that the damage or destruction was effected without a lawful excuse. Criminal damage is a result crime and the ‘consequences’ element of the actus reus of this offence will be satisfied by proof that the destruction of or damage to the property was caused by D’s conduct. If all of these elements are proved by the prosecution (i. e. the jury is satisfied beyond reasonable doubt), then the actus reus of criminal damage is established.
However, although proof of actus reus is a necessary precondition of conviction, where the offence is one which requires proof of mens rea – as is criminal damage – proof of actus reus alone is not sufficient to convict a defendant. The prosecution also needs to establish that the defendant committed the actus reus of the offence with the appropriate mens rea. If you return to the definition above you will see that the mens rea is expressed as an intention to destroy or damage property or being reckless as to whether any such property would be destroyed or damaged.
Therefore the prosecution would need to prove that the defendant either intentionally or recklessly destroyed or damaged property belonging to another. The meaning of the terms intention and recklessness are considered in Chapter 5 of this guide Activity 2. 6 a. What mens rea needs to be proved on the part of a defendant who has been charged with criminal damage contrary to s. 1(1) of the Criminal Damage Act 1971? b. What is the conduct element of the offence of criminal damage contrary to s. 1(1) of the Criminal Damage Act 1971? 2. 4 Lawful excuse.
Before leaving the offence of criminal damage, the element ‘without lawful excuse’ needs clarification. Although it could be expressed as an element of the actus reus of the offence, it could also be said that if the defendant knew he had a lawful excuse then he or she neither intended nor was reckless as to causing criminal damage. It follows that, under these circumstances, the defendant would not have the mens rea for the offence. Similarly, even if the defendant did not have a lawful excuse, but honestly believed that he did, then that mistaken belief would negate any criminal liability.
See Chapters 11–12. Consider now the situation where the defendant did have a lawful excuse but, at the time he destroyed or damaged the property belonging to another, was not aware of this fact. Imagine that the defendant is lawfully in possession of an item of property which belongs to V and the defendant deliberately destroys that property. If you consider the definition above it will be clear that D is guilty of criminal damage. The actus reus and mens rea are established. Now imagine that, before the defendant destroyed the property, V had emailed him instructing him to destroy it.
The email has reached D’s mailbox but D has not checked his emails and therefore does not know of V’s instruction. Is D guilty of criminal damage? If, as stated above, without lawful excuse is an element of the offence of criminal damage, it could be argued that as D has – albeit unknown to him – a lawful excuse, he cannot be guilty of this offence. In order to convict D the prosecution must prove all of the elements of the offence with which D is charged (see Deller (1952)). However, it could be argued that rather than being an element of the offence itself, a lawful excuse is, in fact, a defence.
If this is the case, then on the basis of the decision in the case of Dadson (1850) 2 Den 35, D may be found guilty of criminal damage. Which outcome do you prefer? Criminal law Chapter 2 The elements of an offence page 17 Activity 2. 7 Online research Find the definition of the offence of robbery contrary to s. 8 of the Theft Act 1968 using Westlaw. You can access this by logging on to the student portal and then going to the databases in the Online Library. Summary Every ingredient of an offence must be proved before a defendant may be found guilty of that offence.
This is subject to the defendant having a lawful excuse for his or her conduct. Please note that you will always find the elements of an offence in its definition. page 18 University of London International Programmes Reflect and review Look through the points listed below: Are you ready to move on to the next chapter? Ready to move on = I am satisfied that I have sufficient understanding of the principles outlined in this chapter to enable me to go on to the next chapter. Need to revise first = There are one or two areas I am unsure about and need to revise before I go on to the next chapter.
Need to study again = I found many or all of the principles outlined in this chapter very difficult and need to go over them again before I move on. Tick a box for each topic. Ready to move on Need to revise first Need to study again I can find the definition of a criminal offence. ? ? ? ? ? I can demonstrate an understanding of the constituent ? elements of that definition, i. e. actus reus and mens rea. I can demonstrate an awareness of the limits of the terms ‘actus reus’ and ‘mens rea’ when used without further clarification. ? ? ?
If you ticked ‘need to revise first’, which sections of the chapter are you going to revise? Must revise 2. 1 General analysis of criminal offences 2. 2 Limitations on the value of the Latin terms actus reus and mens rea 2. 3 Proof of the ingredients of an offence 2. 4 Lawful excuse Revision done ? ? ? ? ? ? ? ? Before you continue to the next topic listen again to audio presentation 2 to recap and consolidate what you have learnt. 3 Actus reus: the conduct element Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 3. 1 3. 2 3. 3 3. 4 3.
5 3. 6 3. 7 Voluntariness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Omissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Imposition of liability for an omission to act . . . . . . . . . . . . . . . .22 Duty to act under the common law . . . . . . . . . . . . . . . . . . . .24 Distinguishing between act and omission . . . . . . . . . . . . . . . . . 26 New categories of duty. . . . . . . . . . . . . . . . . . . . . . . . . . . 27 The ‘circumstances’ element of the actus reus . . . . . . . . . . . . . . . 28 Reflect and review .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 page 20 University of London International Programmes Introduction The actus reus of any offence will be found in the definition of that offence. It will include: ? wrongful conduct on the part of the defendant. This may be an act or an omission where the defendant is under a duty to act. In either case, to constitute wrongful conduct the act or omission must be voluntary. the existence of one or more specified circumstances in the case of a result crime, a particular consequence caused by D’s conduct. ? ?
This chapter will examine, in outline, what the criminal law understands by voluntary conduct and, in detail, the scope of liability for omissions. Chapter 4/5 will deal with causation in relation to the consequences element of the actus reus of result crimes. Essential reading and listening ? Wilson, Chapter 4: ‘Actus reus’, Section 4. 5 ‘Exceptions to the act requirement’, Part C ‘Omissions’. Audio presentation 4. Listen to this before you go any further with this topic. Lane LJ’s judgment in R v Stone and Dobinson  1 QB 345. (Included in your study pack. ) ? ? Learning outcomes
By the end of this chapter and the relevant readings you should be able to: ? ? ? ? explain what is meant by voluntary conduct explain the distinction between an act and an omission assess whether an offence is capable of being committed by omission understand the notion of a duty to act and under what circumstances such a duty is likely to be imposed identify the circumstances under which a duty to act might change or cease recognise the circumstances element of the actus reus of an offence be able to identify when a state of affairs might amount to the actus reus of an offence.
? ? ? Criminal law Chapter 3 Actus reus: the conduct element page 21 3. 1 Voluntariness Although the conduct element of the actus reus of an offence usually requires proof of a positive act on the part of the defendant, some offences can be committed by an omission to act. Whether the prohibited conduct is an act or an omission, such conduct must be voluntary conduct on the part of the defendant.
In the case of Woolmington v DPP  AC 462 Viscount Sankey ruled that, subject to limited exceptions, the burden was on the prosecution to prove the defendant’s guilt beyond reasonable doubt. One of the points he emphasised in relation to the defendant’s conduct was that: ‘The requirement that it should be a voluntary act is essential… in every criminal case’.
Some years later, in the case of Bratty v Attorney General for Northern Ireland  3 All ER 523 HL, Lord Denning said: No act is punishable if it is done involuntarily: and an involuntary act in this context… means an act which is done by the muscles without any control by the mind such as a spasm, a reflex action or a convulsion; or an act done by a person who is not conscious of what he is doing such as an act done whilst suffering from concussion or whilst sleepwalking…
It follows, therefore, that in order to attract criminal liability a defendant’s conduct must be voluntary – that is, it must be a willed bodily movement (or lack of action where D is under a duty to act). For example, if D does not control his car and it hits something causing damage, he will not be criminally liable if the reason he could not control the car was because, for example, he was being attacked by a swarm of bees. Brake failure through no fault of the defendant would equally give the driver no control over the situation (see Burns v Bidder  2 QB 227).
Similarly, if the same thing happened because he had a heart attack or epileptic fit, his conduct is involuntary. Where a defendant has no control over what he is doing he is said to be acting in a state of automatism which, like insanity its close cousin, is a defence to criminal liability. Automatism and insanity will be looked at in detail in Chapter 12. 3. 2 Omissions The conduct element of the actus reus usually requires proof of a positive act on the part of the defendant.
Although it could be said that we owe negative duties to others – such as not to kill them, not to injure them and not to steal from them – there is no general liability for failure to act under the common law of England and Wales. A stranger, for example, would not incur criminal liability for watching somebody drown in a swimming pool even if that person could have been saved with very little effort on the stranger’s part. The stranger would, however, incur criminal liability if he or she carried out a positive act, such as holding the other’s head under the water, which caused or contributed to the death.
Either way, the victim has died, but in the situation where the stranger merely watched the victim drown without doing anything, the victim would have died in any event, whether or not the stranger had been there. † † Self-reflection Consider the example of the stranger (above). Do you think a general duty to act should be imposed under English law? Do you think the position would be different had it not been the stranger watching but: ? ? Although some jurisdictions have adopted a general principle of liability for failure to act – e. g. France – many, including England and Wales, have not done so.a lifeguard the victim’s page 22 ? ? ? ? ?
University of London International Programmes brother aunt father schoolteacher flatmate. 3. 3 Imposition of liability for an omission to act A crime can be committed by omission, but there can be no omission in law in the absence of a duty to act. The reason is obvious. If there is an act, someone acts; but if there is an omission, everyone (in a sense) omits. We omit to do everything in the world that is not done. Only those of us omit in law who are under a duty to act (Glanville Williams, Textbook of criminal law, pp. 148–149. )
There are circumstances where the law does impose on a person a duty to act. Sometimes a statute will specifically state that the actus reus of an offence is committed by omission, for example, by virtue of s. 1(1) of the Children and Young Persons Act 1933 it is an offence to wilfully neglect a child. This is an offence of ‘mere omission’. Offences of ‘mere’ omission are rarely found at common law. Sometimes the courts will determine that a particular offence may be committed by omission even though the definition of that offence does not specifically provide for this – for example murder.
See Gibbins and Proctor  13 CAR 134. Self-reflection What might be the arguments in favour of imposing a general legal obligation to go to the assistance of someone who is in the process of committing or has attempted to commit suicide? Should the parents of an adult child attract criminal liability if they observe (without assisting) their child committing suicide? Can you think of any arguments against imposing such a general obligation? Where a statute specifically provides that an actus reus is committed by omission it will be clear that a duty to act has been imposed on a particular class of person.
The scope of any such duty will also be clear. Where the offence is not one satisfied by proof merely of prohibited conduct on the part of the defendant, but is a result crime – an offence such as murder or manslaughter which requires proof of a consequence arising from the defendant’s conduct – it will fall to the court to determine whether a defendant’s inaction might result in criminal liability. Where an offence is capable of being committed by omission it will need to be determined whether the defendant was under a duty to act and is therefore liable for failing to do so.
Where it is found by the court that a defendant was under a duty to act in a particular situation and has unreasonably failed to do so, the burden remains on the prosecution to prove all the other ingredients of the offence (i. e. any remaining elements of the actus reus and the mens rea required for the particular offence with which the defendant has been charged). So, if the court finds that A was under a duty to B, if A has allowed B to die and has been charged with murder or manslaughter, it will still need to be proved that A’s conduct was unlawful and that it caused B’s death.
The relevant mens rea for the particular offence will also need to be established. 3. 3. 1 Is the offence capable of being committed by omission? Essential reading ? Wilson, Chapter 4: ‘Actus reus’, Section 4. 5 ‘Exceptions to the act requirement’, Part C. 3 ‘Omissions: the common approach’. Criminal law Chapter 3 Actus reus: the conduct element The rule of thumb is that any offence can be committed by omission, unless the definition of the offence excludes this possibility.
Offences which have been interpreted by the courts as capable of being committed by omission include murder (Gibbins and Proctor  (above)) and gross negligence manslaughter. Most of the cases referred to below are manslaughter cases. Murder and manslaughter are common law offences. Offences which cannot be committed include unlawful act manslaughter: Lowe  QB 702 and assault. See also the case of Santana-Bermudez  in which the defendant was convicted of an assault. page 23 Activity 3. 1 Read Wilson, Chapter 11: ‘Non-fatal offences’, Section 3 ‘Offences protecting personal autonomy’, Part A.
2 ‘Battery’. If assault cannot be committed by omission why then was the defendant in Santa-Bermudes convicted? Activity 3. 2 Can the word ‘acts’ in a statute be construed as being satisfied by an omission? See Ahmad  Crim LR 739 and the discussion in Wilson, Chapter 4: Section 4. 5 ‘Exceptions to the act requirement’, Part C. 3 ‘Omissions: the common law approach’. 3. 3. 2 Was the defendant under a duty to act? Once it has been established that the offence is capable of being committed by omission, the court must determine whether the defendant was under a duty to act.
The duty, where it exists, is not an onerous one. A person is not expected to put his or her own life at risk. Rather the question that will be considered by the courts is whether a defendant who was under a duty to act has discharged that duty to a reasonable standard. What is reasonable will depend upon the circumstances in each case. For example, whereas a stranger may, without doing anything to help, watch with interest a person drowning in a lake, a lifeguard who has been appointed to ensure the safety of people at, for example, the seaside or in a swimming pool will be under a duty to act.
Although the lifeguard must discharge any such duty to a reasonable standard, he will not be expected to put his own life in danger. He would merely be expected to do that which a reasonable lifeguard would do. If there was any particular danger to him – e. g. a shark swimming in the sea – he would discharge his duty by obtaining proper assistance. He would not be expected to swim into the zone of danger or put his own life and safety at risk in any other way. Nonetheless, the lifeguard must discharge his duty to a reasonable standard.
What he did or did not do in attempting to discharge that duty will be judged according to how the court considers a reasonable lifeguard would have acted under the particular circumstances. It is thus an ‘objective’ test. Therefore even if a defendant thought he was doing his best, if that ‘best’ was an ‘incompetent best’ it is unlikely to have been sufficient to discharge his duty. See Stone and Dobinson in 3. 4 below. Most people, of course, will act over and above any duty the law may have imposed upon them and many will act when they are under no legal duty at all.
It is difficult, for example, to imagine a passer-by who sees a person drowning or witnesses an accident not even bothering to call one of the rescue services. It should be remembered, however, that they are under no duty to do so and if they do not do anything they will not attract any criminal liability. There is a difference, however, between what we might term ‘moral’ duty to act and a ‘legal’ duty to act. No legal sanction is imposed for breach of a moral duty – although there may be social opprobrium. However many legal duties could be said to have arisen from moral ones. As Lord Coleridge CJ said in the case of Instan : page 24 University of London International Programmes.
It would not be correct to say that every moral obligation involves a legal duty; but every legal duty is founded on a moral obligation. A legal common law duty is nothing else than the enforcing by law of that which is a moral obligation without legal enforcement. Self-reflection It is an offence under the law of England and Wales not to wear a seat belt when travelling in a motor car. Can this duty be said to have arisen from any moral obligations? The issue for the courts in developing the law and the legislature in enacting law is: when should a legal duty to act be imposed and what should be the scope of any such duty?
The boundaries are very unclear. Although a parent is under a legal duty towards his or her child, should a legal duty be imposed on someone in respect of their brother or sister? Their neighbour? Or perhaps someone to whom they have supplied illicit drugs, as in Evans (2009) and Khan and Khan (see section 3. 6 below)? Are you under a duty towards your friend? It is likely to depend upon the situation. What might be the scope of any such duty which may exist? In Lewin v CPS  EWHC Crim 1049 a decision by the Crown Prosecution Service not to prosecute was upheld.
In this case the defendant, at the end of a car journey in Spain with his friend, left his friend (who was intoxicated) asleep in the car. It was summer and the weather was hot. His friend died. The court held that the defendant was only responsible for the welfare of his passenger whilst the car was in motion. His duty towards his friend did not continue because the risk of death was not reasonably foreseeable. In other words the court considered that the reasonable man would not have foreseen that occurrence under those particular circums.