Legal definitions according to Belgian law:
Any act which consists of or may include sexual penetration, of whatever nature and by whatever means, committed on a person who does not consent or with the assistance of a person who does not consent, constitutes the crime of rape.
Performing a sexual act on a person who does not consent, with or without the assistance of a third party who does not consent, or causing a sexual act to be performed by a person who does not consent.
Is also considered sexual assault:
Causing a person who does not consent to be present during sexual acts or sexual abuse, even if that person is not required to take part.
Consent implies that it has been freely given. This is assessed in the light of the circumstances of the case. Consent cannot be inferred from the victim’s simple lack of resistance. Consent may be withdrawn at any time before or during the sexual act.
Consent does not exist if the sexual act has been committed by taking advantage of the victim’s vulnerability as a result of, inter alia, fear, the influence of alcohol, narcotics, psychotropic substances or any other substance with a similar effect, an illness or a disability, which has affected free will.
In any case, consent does not exist if the sexual act is the result of a threat, physical or psychological violence, coercion, surprise, a ruse, or any other criminal conduct.
In any case, consent does not exist if the sexual act is committed on an unconscious or sleeping victim.