Evaluate the defence of consent
Arguably consent is not a defence as consent means there has been no unlawful act. It is an area of the law that has attracted some criticism and calls for reform. The Law Commission has expressed several views on the rules surrounding consent, as part of different reviews.
The relevant considerations are in what circumstances a person is able to give consent and whether genuine consent is given. There seems to be a lack of clarity over the reasons behind allowing or denying consent defence.
Level of harm
It seems grave harm is a factor in considering consent (Barnes (2004)).
So despite genuine consent a defendant who causes serious harm may still be liable. In Leach  the defendants nailed the victim to a wooden cross, piercing his hands with six inch nails. Despite the fact the victim had organised to be crucified and the defendants were acting at his request, they were found guilty of a S18 offence under the Offences Against the Person Act 1861 (OAPA 1861).
However it can be seen as inconsistent that consent is allowed in situations where injuries are common. Boxing is a dangerous sport where opponents aim to injure one another, to the extent that a doctor must be ringside Watson v BBBC , but consent can apply. The horseplay exemption meant defendants who had caused serious harm by setting on fire to the flame resistant clothing had their convictions quashed on appeal (Aitken (1992)).
The Law Commission agrees law should set a limit to the injury to which a person may consent (
Consent and Offences Against the Person) and allow for public policy exemptions.
Consent may be present, but may not be sufficient if the aim of the activity is to cause harm.
Defendants participated in sadomasochistic activity and no one suffered permanent injury. Defendants argued the acts were consensual but the judge did not allow defence. On appeal the court confirmed consent could be only be used in cases of battery, causing any greater injury was not in public interest. Lord Templeman said
..violent cruelty is injurious and predictably dangerous. I am not prepared to invent a defence of consent for sadomasochistic encounters… (Brown (1993)).
The need to protect the vulnerable raised as an issue with consent. A defendant was found guilty of ABH in relation to tattooing two teenage boys who gave their consent. It was held the boys were unable to appreciate the nature of the act so could not give true consent (Burrell v Harmer (1967)).
However, protection of young victims is not always maintained in UK law. Defendant often severely beat an 8 yr old, with a garden cane, he argued such action was reasonable and necessary because the victim was a difficult child. The European Court of Human Rights found the UK failed to provide adequate protection to children in such situations (A v UK (1998)).
The application of the law in relation to whether consent is valid seems unclear, especially in terms of the victim’s necessary knowledge.
In cases of fraudulently obtaining consent conflicting conclusions have been reached. In Richardson (1998) a suspended dentist, who treated patients was found not guilty of assault. However in Dica (2004) the defendant, knew he was HIV positive had unprotected sex with the victims who became infected and he was found guilty.
Mistaken belief in consent has been allowed. Defendants and the victim often indulged in horseplay and the defendants believed the victim consented when they dropped him from a balcony. They were convicted of S20 offences under OAPA 1861 but the Court of Appeal held their belief in the victim’s consent should have been considered (Richardson and Irwin (1999)).
This seems in stark contrast to decisions in cases where genuine consent existed but was not allowed, such as Leach  and Brown (1993).
The Law Commission has put forward that
subsisting, free and genuine agreement should count as consent to a sexual act by another (
Consent in sexual offences). The Sexual Offences Act 2003 was later brought in but problems still exist in some cases .
The extent to which individual freedom to engage in consensual activity is upheld seems unclear.
Lord Lane noted
..it is an essential element of an assault that the act is done contrary to the will and without the consent of the victim, it’s not in the public’s interest that people should try to cause, or should cause, each other bodily harm no reason... (Attorney General’s References (No6 of 1980) 1981).
However in Wilson (1996) a defendant branded his initials, with a hot knife, on his wife buttocks. She had requested the homemade tattoo but had to seek medical attention for burns. He was convicted of ABH under S47 of OAPA 1861. On appeal it was found it was a situation of
personal adornment and not in the public interest to criminalise such consensual acts.
In some cases, such as Aitken (1992), consent is accepted, despite serious harm. In other cases of harm the courts will intervene despite presence of consent. In his dissenting judgement Lord Mustill commented
.. the state should interfere with the rights of the individual no more than is necessary... (Brown (1993)).
This confusion raises the issue whether consent should be reflected in sentencing but not in the verdict. The Law Commission’s 1994 consultation paper
Consent and Offences Against the Person discusses the view that a person's body is their own and that the law has no place in dictating what can be done with it. The approach is rejected with the Commission highlighting illegal drugs as an example where the law limits complete bodily freedom.
Consent cannot be given for killing. This raises complex arguments in relation to euthanasia. If patient is capable of giving consent then a doctor has no authority to treat them without their consent but a patient is not allowed to ethically refuse treatment in order to bring about their own death.
There are no legal right to suicide or for others to be involved in helping someone to die. Concerns exist that allowing some competent patients to decide to die would leave opportunity for vulnerable people to be ‘killed off’. Legislation to allow euthanasia would allow private citizens, doctors, to kill others.
The illegality of euthanasia has been challenged in number of cases.. The House of Lords and European Court of Human Rights have that found Article 2 of European Convention on Human Rights does not provide right to die and the protection of vulnerable citizens is of paramount importance. (Pretty (2002)).
Assisted suicide remains unlawful under the Suicide Act 1961. It is unclear if those who assist someone to travel abroad to commit suicide may be liable for prosecution (R (on application of Purdy) v DPP (2009)).
Commenting on life prolonging treatment Lord Goff noted
.. the law draws a crucial distinction between cases in which a doctor decides not to provide, or to continue to provide, for his patient treatment or care which could or might prolong his life, and those in which he decides.. actively to bring his patient's life to an end... (Airdale NHS Trust v Bland ).
However, the family of a patient suffering from
minimally conscious state condition argued that she was in pain and her life support should be withdrawn but this was opposed by the doctors. High Court judge ruled that the life sustaining treatment could not be stopped, stating:
.. although not an absolute rule, the law regards the preservation of life as a fundamental principle... (W v M and S and NHS PCT (2011)).
This remains a very controversial area of law which involves such wide ranging issues which infringe on morals and ethics. Most agree for judges to change position through case law would be wrong and inappropriate use of power and any changes should be through legislation.