The common law and the physical liberty of the individual

[t]he notion that, prima facie, any physical contact or threat of it is unlawful, is a right in each person to bodily integrity. That is to say, the right in an individual to choose what occurs with respect to his or her own person. In his Commentaries, Blackstone wrote:
[T]he law cannot draw the line between different degrees of violence, and therefore totally prohibits the first and lowest stage of it; every man's person being sacred, and no other having a right to meddle with it, in any the slightest manner.

It is the central thesis of the common law doctrine of trespass to the person that the voluntary choices and decisions of an adult person of sound mind concerning what is or is not done to his or her body must be respected and accepted, irrespective of what others, including doctors, may think is in the best interests of that particular person. To this general thesis, there is an exception: a person cannot consent to the infliction of grievous bodily harm without a 'good reason' (Attorney-General's Reference [No 6 of 1980][1981] EWCA Crim 1; , [1981] 1 QB 715, 719). But save in this exceptional case, the common law respects and preserves the autonomy of adult persons of sound mind with respect to their bodies. By doing so, the common law accepts that a person has rights of control and self-determination in respect of his or her body which other persons must respect. Those rights can only be altered with the consent of the person concerned. Thus, the legal requirement of consent to bodily interference protects the autonomy and dignity of the individual and limits the power of others to interfere with that person's body (309 - 310).