18 Pa.C.S.A. §311.  Consent.

(a)  General rule.–The consent of the victim to conduct charged to constitute an offense or to the result thereof is a defense if such consent negatives an element of the offense or precludes the infliction of the harm or evil sought to be prevented by the law defining the offense.

(b)  Consent to bodily injury.–When conduct is charged to constitute an offense because it causes or threatens bodily injury, consent to such conduct or to the infliction of such injury is a defense if:

(1)  the conduct and the injury are reasonably foreseeable hazards of joint participation in a lawful athletic contest or competitive sport; or

(2)  the consent establishes a justification for the conduct under Chapter 5 of this title (relating to general principles of justification).

(c)  Ineffective consent.–Unless otherwise provided by this title or by the law defining the offense, assent does not constitute consent if:

(1)  it is given by a person who is legally incapacitated to authorize the conduct charged to constitute the offense;

(2)  it is given by a person who by reason of youth, mental disease or defect or intoxication is manifestly unable or known by the actor to be unable to make a reasonable judgment as to the nature or harmfulness of the conduct charged to constitute the offense;

(3)  it is given by a person whose improvident consent is sought to be prevented by the law defining the offense; or

(4)  it is induced by force, duress or deception of a kind sought to be prevented by the law defining the offense.