In law knowledge is one of the degrees of mens rea that constitute part of a crime. For example, in English law, the offence of knowingly being a passenger in a vehicle taken without consent (TWOC) requires that the prosecution prove, not only that the defendant was a passenger in a vehicle and that it was taken by the driver without consent, the prosecution must also prove that the defendant knew that it was taken without consent.Under the principle of ignorantia juris non excusat, ignorance of or mistake about the law is no defence. The mens rea of knowledge refers to knowledge about certain facts. It is "a positive belief that a state of affairs exists."Knowledge can be actual, constructive, or imputed.