In Criminal Law, an offence committed against a person refers to an offence which directly causes physical harm to another person. Such offenses may amount to assault, fatal offense, sexual offenses, etc. In the given case scenario, Neil has engaged in a consensual sexual intercourse with his sado- masochism mistress Kate despite being aware of the fact that he is infected with HIV positive.
Sexually transmitted disease may fall under sections 18 and 20 of the Offenses against a person act 1861 where issues relating to sexual transmission of HIV are often dealt under section 20 of the Act and are often referred to as recklessness behaviour (Gibson 2016). It implies that defendant foresaw that the victim might be infected with the HIV disease if they engage in an unprotected sexual activity. Any person who does not inform the partner about his or her HIV infection before sexual intercourse, shall be considered as reckless and is liable to be punished under section 20 of the OAPA 1861.
Where consensual activity is involved, it was held by the UK court in R v Donovan  AER 207 that no person is allowed to give consent to commit a crime. In R v Brown, court held that in case of engaging in consensual sexual activity for sado masochism, the consent of woman given shall not be valid if the act causes grievous bodily harm to the woman. Therefore, in the given case, Neil is liable under section 20 of the OAPA for being reckless and causing bodily harm to Kate.
Gibson, M., 2016. Getting Their “Act” Together? Implementing Statutory Reform of Offences against the Person. Criminal Law Review, (9), pp.597-617.
R v Donovan  AER 207