The law in (edit!) England & Wales used to be absolutely clear: STI infection during consensual sex was not assault, even when the infection was deliberately concealed from the partner.
But in the past couple of years, there have been three successful prosecutions of men for sexual transmission of HIV. They're going through various retrials and appeals, but the basic question remains:
Should sexual transmission of HIV be a criminal offence?
What about when someone lies about their HIV status in order to get their partner to consent to unprotected sex?