In law, knowledge is one of the degrees of '' mens rea'' that constitute part of a

crime In ordinary language, a crime is an unlawful act punishable by a state or other authority. The term ''crime'' does not, in modern criminal law, have any simple and universally accepted definition,Farmer, Lindsay: "Crime, definitions of", in Ca ...

. For example, in English law, the offense 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, but also that the defendant knew that it was taken without consent. Under the principle of ''

ignorantia juris non excusat In law, (Latin for " ignorance of the law excuses not"),''Black's Law Dictionary'', 5th Edition, pg. 672 or ("ignorance of law excuses no one"),''Black's Law Dictionary'', 5th Edition, pg. 673 is a legal principle holding that a person who is ...

'', ignorance of or mistake about the law is no defense. 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.

Actual knowledge

A defendant does not have ''actual knowledge'' if they believe something to the contrary. The standard is subjective and the belief of the defendant need not be reasonable, only honest.Herring (2004) ''p.''171 For example, in '' R v. Williams'' the defendant intervened in what he thought was a

mugging Mugging or mugger may refer to: * Mugger, a footpad * Mugger crocodile, a species native to India, Nepal, and Pakistan * ''Muggers'' (film), a 2000 Australian movie directed by Dean Murphy * Mugging, a slang term for overacting * Mugging, a typ ...

but was in fact a

citizen's arrest A citizen's arrest is an arrest made by a private citizen – that is, a person who is not acting as a sworn law-enforcement official. In common law jurisdictions, the practice dates back to medieval England and the English common law, in which ...

. His mistake was upheld as a defense against a charge of

assault An assault is the act of committing physical harm or unwanted physical contact upon a person or, in some specific legal definitions, a threat or attempt to commit such an action. It is both a crime and a tort and, therefore, may result in cri ...

. In '' Beckford v. R'' the defendant was a

police officer A police officer (also called a policeman and, less commonly, a policewoman) is a warranted law employee of a police force. In most countries, "police officer" is a generic term not specifying a particular rank. In some, the use of the ...

who shot and killed V. Beckford claimed that he believed that V was shooting at him. It was found that the correct test was whether D "honestly belied" facts which, if true, would establish a defense. The reasonableness of the belief would be evidential in finding whether it was truly believed.

Constructive knowledge

Knowledge is also found where a defendant suspects that circumstances exist and "deliberately decides not to make any further enquiries" in case his suspicions prove well founded. A common example is a person who purchases significantly inexpensive and unprovenanced but desirable items from a stranger. Such a person is likely to be fixed with ''constructive knowledge'' that the items were

stolen Stolen may refer to: * ''Stolen'' (2009 Australian film), a 2009 Australian film * ''Stolen'' (2009 American film), a 2009 American film * ''Stolen: The Baby Kahu Story'' (2010 film), a film based on the real life kidnapping of baby Kahu Durie ...

Imputed knowledge

This is relevant in

strict liability In criminal and civil law, strict liability is a standard of liability under which a person is legally responsible for the consequences flowing from an activity even in the absence of fault or criminal intent on the part of the defendant. Un ...

offenses and in

corporate crime In criminology, corporate crime refers to crimes committed either by a corporation (i.e., a business entity having a separate legal personality from the natural persons that manage its activities), or by individuals acting on behalf of a corpo ...

. For example, if a bar manager delegates his duties to others and those others know of unlawful activities on the premises, the manager can be fixed with ''imputed knowledge'' of the unlawful activities.''Ferguson v. Weaving'' 9511 All ER 412 (England)

References

Bibliography

* Criminal law Forensic psychology {{law-term-stub