Canadian Criminal Law/Defences

General Principles
An accused person who is able to raise a defence can escape criminal liability for an offence that they could otherwise be convicted for.

Defences are often categorized as follows:
 * Justification: a justifiable act is one that makes out the offence but is justified by the external circumstances in which the act was committed. (e.g. self-defence)
 * Excuse: a criminal act is excused where the accused would have committed an undesirable criminal offence, for which punishment would be morally inappropriate due to the extenuating circumstances. (e.g. offences due to mental infirmities, duress)
 * Affirmative Defence: a defence that, if proven, will eliminate liability despite all the elements of the offence having been made out
 * Negating Defence: a defence that negates one more of the essential elements of the prosecution's case.

Under s. 794, the burden is on the defendant to prove an exception or excuse:

Excuses and justifications "do not negative the mens rea rather they operate by justifying or excusing what would otherwise be criminal conduct".

Raising a Defence
Before the trier-of-fact can consider a defence, thus requiring the crown to disprove at least one of the elements of the defence beyond a reasonable doubt, there must be an "air of reality" to the defence.

The purpose of the air of reality test is to prevent "outlandish defences" being put to the jury that would be "confusing and would invite unreasonable verdicts."

Topics

 * Intoxication
 * Automatism
 * Provocation
 * Necessity
 * Duress
 * Entrapment
 * Self-Defence and Defence of Another
 * Defence of Property
 * Acting in Authority
 * Officially Induced Error
 * Corrective Force
 * Accident and Mistake
 * Alibi
 * De Minimus
 * Due Diligence
 * Consent
 * Alternative Suspect Defence
 * Abandonment