A discussion of homicide
Under the facts of the scenario, Vincent had died and this would warrant a discussion of homicide. The actus reus of homicide is the unlawful killing of another. It would be unlikely that the parties concerned would be liable for murder as it seems they do not have requisite mens rea of malice aforethought for the offence.
Criminal Liability Of Flavia.
If Flavia is charged with constructive manslaughter, the prosecution would have to show an unlawful act which is also dangerous, caused the death of Vincent. The prosecution would be likely to rely on s23 Offences Against the Persons Act 1861 where the unlawful act is administering a noxious thing; which was successfully argued in Cato.
Previous case law on manslaughter and drug supply cases has been far from consistent, but the House of Lords (HL) decision of Kennedy (No 2) was held by Ormerod as a ‘most welcomed conclusion' to the drug-supply case law. In the case it was stated that where a victim of a sound mind injected himself as a result of ‘free, voluntary and informed decision' this would break the chain of causation. In the scenario it is stated that ‘Vincent injects himself', we can safely assume that Flavia had not administered the injection directly and it was a ‘free, voluntary and informed decision' made by Vincent which breaks the chain of causation. It must also be presumed that factors such as age, mental conditions or improper pressure have not affected the decision of Vincent to self-inject, if they had, Flavia could be liable; which is more likely as he is at a party. If Vincent was an addict, Clarkson would question whether taking drugs would be ‘free and voluntary'. In Kennedy (No 2) it was stated that, in relation to the scenario, that the ‘act of supplying the drugs by [Flavia], without more, could not harm [Vincent] in any psychical way, let alone cause his death'.
HL did not rule out scenario where two people are ‘acting together'. This left open a ‘narrow circumstances' which Flavia would be liable for death of Vincent, apart from where there is direct injection to the deceased. In the scenario, Flavia used her belt as tourniquet to lift a vein and this was similar to the case of Rogers (where the defendant was convicted). But this was specifically stated as ‘wrongly decided' by Lord Bingham and we can assume that this would not amount to ‘acting together'. Additionally Kennedy (No 2) also stated; preparation and handing the syringe to victim will not constitute ‘acting together' to give rise to liability for the death of Vincent.
Lord Bingham stated ‘nothing in this opinion should be understood as applying to manslaughter caused by negligence'. Therefore we may be able to argue that Flavia is liable for gross negligence manslaughter for the death of Vincent.
It is more likely that Flavia would be charged with gross negligence manslaughter, prosecution would have to prove the criteria laid down by Lord Mackay in the case of Adamako (which applies to all gross negligence cases). It would first of all need to be established that the defendant owed a duty of care to victim and the defendant breached that duty of care and this caused the death of Vincent. The breach of duty must be characterised as grossly negligent to constitute a crime; a matter for the jury to decide on.
An omission could be deemed to be the ‘act' which breached duty of care. Evans stated that judge decides whether there is a duty of care between the defendant and victim, as it is a question of law and the jury decides, based on the facts in front of them, whether that duty actually exists.
The case of Evans stated ‘when a person created or contributed to the creation of state of affairs which he knows, or ought reasonably know, has become life threatening, a consequent on him to act by taking reasonable steps to save the other's life will normally arise' , could be adopted to show that a duty of care existed between Flavia and Vincent through the supply of the drugs. In the scenario it states that Vincent became unconsciousness with minutes and it could be argued that Flavia ought to have known that assistance was required at this point, she also may have experienced this herself or seen it occur as ‘drugs are often taken at her party'. Flavia did nothing to discharge her duty, which could amount to breach of her duty. It must be shown Flavia caused Vincent's death. Ormeron states that ‘it is sufficient that [Flavia's] breach was a substantial and operative cause of [Vincent's] death, even if it not the sole or main cause'.
Rogers interestingly argues, where voluntary self injection has been made by Vincent and this break the chain of causation how could she be liable for Vincent's subsequent illness as it was he who created the dangerous situation?
Criminal Liability Of Kristina
Kristina may be liable under gross negligence manslaughter. To establish a duty of care it would need to be discussed whether their relationship of boyfriend and girlfriend gives rise to duty of care. Parental or spousal relationships automatically give rise to a duty of care but in this case they are merely boyfriend and girlfriend. It would be required to establish the depth of the relationship and the level of interdependence between the two. Case of Evans stated that a duty of care did not arise between two half-sisters but the case of Sinclair stated that two friends who ‘almost lived together as brothers' in addition to jointly participating in dangerous conduct may give rise to duty of care, but Kristina didn't participate with Vincent in taking the drugs therefore it may not be applicable. There is no such case-law based on relationship of girlfriend and boyfriend owing a duty to each other, therefore it is unclear whether a duty of care would arise between Kristina and Vincent.
It could also be argued that Kristina assumed responsibility for Vincent and therefore she has a legal duty to act. Case law states; putting the victim in recovery position or pouring water over the deceased does not give rise to voluntary assumption of responsibility and following this authority; moving Vincent into another room and putting him on the bed is also unlikely to do so. A determining factor would be whether Vincent would expect Kristina to assist just before he lapsed into unconsciousness. Clarkson argues that, in the case of Kristina, a duty of care between her and Vincent would arise if she is under position of responsibility whereby others reasonable expect her to act. Ormerod provides an example of duty of care where a victim becomes reliant on defendant where the victim overdoses and relies on the defendant to help, but by moving him to another room he is out of sight from others, which are exactly the facts of the scenario, which therefore may give rise to criminal liability of gross negligence manslaughter for Kristina, but may not apply to Tom as there may not be such reliance.
But this is a matter for the jury to decide whether Tom and/or Kristina have voluntarily assumed a duty of care. Particularly in relation to Kristina, whether it was reasonable to call a taxi, instead of an ambulance.
Criminal Liability Of Tom
Tom could also be charged with gross negligence manslaughter. The case of Adamako illustrated breach of doctor-patient relationship. But it must be noted that Tom is at a party and also a ‘little more than drunk'. It is arguable whether this gave rise to a duty of care by classifying the relationship between him and Vincent as a doctor-patient one. Taking the example in Sinclair where Johnson (house owner) was not under a duty of care because he did not know the deceased, this could be applicable here on the basis that Tom does not know Vincent, he could be described as being in the ‘wrong place at the right time' to offer advice to Kristina, whilst ‘a little more than drunk'. Again, it would be for the jury to decide on this matter.
Additionally, the delay of the taxi would be unlikely to constitute intervening act because it was arguably not significant or reasonably foreseeable; only ‘significant' intervening acts will break the chain of causation. It must be stated that all of them could be convicted of gross negligence manslaughter, not just one of them.
CMV Clarkson, Understanding Criminal Law (4th edn, Sweet and Maxwell, Gosport 2008)
Clarkson & Keating, Criminal Law Text and Materials (6th edn, Sweet and Maxwell, Beccles 2007)
Finch and Fafinski, Law Express: Criminal Law (2nd edn, Pearson 2009)
Farmer, ‘MacAngus (Kevin) v HM Advocate: Practical, but nonetheless principled?'  Edin. L.R 502
Ormerod, ‘Manslaughter: unlawful act - heroin supplied by defendant and self-administered by deceased'  Crim LR 224
Ormerod, ‘R v Evans (Gemma): Manslughter - gross negligence - deceased supplied by defendant with heroin proved fatal'  Crim LR 662
Rogers, ‘Death, drugs and duties'  Archbold News