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What Does it Mean to be a “Party to an Offence”?

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Under Canadian criminal law, individuals who facilitate or assist in the execution of a crime are treated as culpable as the person who physically carries out the act. This principle is commonly known as “aiding and abetting”. The distinction between aiding and abetting and physically perpetrating the crime is considered legally insignificant by Canadian courts, as those aiding and abetting are defined by the Criminal Code as being an equal participant to the offence. In practical terms, this means that the individual who supplied the weapon could be found guilty of the same offence as the person who fired the shot.

Section 21 of the Criminal Code delineates who is a party to an offence. It includes anyone who physically commits an offence, aids in the commission of an offence through an act or omission, or abets any person in the commission of an offence. The Code also stipulates that two or more individuals who form a common intention to execute an unlawful purpose will be deemed parties to any offence the other person commits in furtherance of that common intention, provided that they knew (or, in limited cases, simply ought to have known) that the offence would be a probable consequence of carrying out their mutually intended unlawful purpose. We acknowledge that this is a complex concept and could cause confusion. By addressing each categorization in turn, we aim to clarify how each operates and demonstrate how someone may become a party to an offence.

Section 21(1)(a) – The Principal Offender

Section 21(1)(a) of the Code states that those who physically commit an offence are a party to that offence. This is relatively straightforward – the individual who personally committed the robbery is a party to the robbery offence. However, it becomes more complex when there are multiple people committing the offence together, and when the offender is committing the offence through an innocent third party.

When two or more individuals actively participate in the commission of a crime, each becomes a co-principal to that offence. In such cases, it is not necessary to determine exactly which person committed which element of the offence. Instead, every act done to commit the offence is deemed to have been committed by all co-principals. For instance, if two accused attack a victim, and both intend to kill him, it does not matter which of the accused delivers the fatal blow. Both, as co-principals, are said to have killed him.

An individual can be a principal to an offence even without physically committing the offence themselves. This occurs when they direct an innocent agent to commit the offence on their behalf. For example, a person can be convicted of forgery where the actual creation of the false document was performed by an innocent agent, if that agent was acting as a “mere instrument” for the offender who controlled their actions. An offence committed by an innocent agent becomes the offence of whoever is directing them, who then becomes the principal offender contemplated by section 21(1)(a).

Section 21(1)(b) – Aiding 

Section 21(1)(b) of the Code provides that those who do or fail to do anything for the purpose of aiding another in the commission of an offence are also a party to that offence. Although this individual has not committed the act themselves, they have nevertheless taken some action, or inaction, intended to assist or help the principal in carrying out the offence. This individual must have actually intended to provide this assistance and they must have known beforehand that the principal intended to commit the crime. This knowledge requirement prevents otherwise innocent people from being captured by section 21(1)(b). For example, if someone lends their friend their car, not knowing that the friend intended to use the car as a getaway vehicle in a robbery, the owner could not be said to be aiding their friend in the commission of the offence. However, if the owner knew that the friend intended to commit this robbery and then provided the vehicle intending to assist them in their robbery, the owner would fall within the scope of section 21(1)(b) and become a party to the offence. A person who is wilfully blind to the intentions of their friend would also be a party to the offence, because wilful blindness “imputes knowledge to an accused whose suspicion is aroused to the point where he or she sees the need for further inquiries, but deliberately chooses not to make those inquiries.”

Failing to act may, in some cases, also amount to aiding in the commission of an offence. An accused who is present at the scene of an offence and who carries out no overt acts to aid or encourage the commission of the offence may nonetheless be convicted as a party if his purpose in failing to act was to aid in the commission of the offence. This is likely to arise if the bystander had a legal duty to act and failed to do so. For the most part, however, mere presence at the scene of a crime and non-interference are both insufficient for aiding and abetting a crime.

A party to an offence may also be excused from criminal liability where the assistance was provided under duress; which essentially means that the conduct was compelled by threats of immediate death or grievous bodily harm and where there was no opportunity to “safely extricate” from the situation.

Section 21(1)(c) – Abetting 

Section 21(1)(c) of the Code provides that those who abet any person in committing an offence are also a party to that offence. “Abetting” means encouraging, instigating, promoting or procuring a crime to be committed, and must be done during the actual commission of the offence. In order to be guilty by abetting, the accused must have intended to encourage the principal in committing the offence. The type of conduct that will be sufficient will vary from case to case. As one example, an accused who was present during a sexual assault who stood by and laughed during the assault, was found to have abetted the assault of the victim through his laughter.

Sufficiency or Insufficiency of Presence:

As previously mentioned, mere presence at the scene of a crime and non-interference are generally insufficient to ground culpability or for a finding of aiding or abetting. Although there are a number of exceptions that depend on the specific circumstances of any situation (for example, the obligations of parents or emergency personnel to act, among many other examples), there is generally no obligation on others to take action to rescue or assist any victim of a crime, and the failure to do so does not result in that person becoming a party to the offence.

Despite this general rule, presence can be evidence of aiding and abetting if accompanied by other factors such as prior knowledge of the intended offence or attendance for the purpose of encouragement. For example, in cases of civil disobedience, the “strength of numbers” serves as a strong source of encouragement, and presence for that purpose could make a person present a party to offences committed during such an event.

Section 21(2) – Common Intention 

Section 21(2) of the Code contemplates a scenario where two or more people have formed an intention in common to carry out an unlawful purpose and to assist each other in accomplishing that purpose. This must be a genuine common intention untainted by duress. If one of these people, in carrying out that common unlawful purpose, commits an independent offence that is different from the intended unlawful purpose, each person who knew that the independent offence was a probable consequence of the shared unlawful purpose becomes a party to that independent offence. In some cases, liability under this section may arise if the independent offence was something that a reasonable person should have known to be a probable consequence of the commonly intended conduct. However, for offences which require a specific intention to be proven, the independent offence must have been subjectively anticipated by each other participant to give rise to criminal liability.


Criminal liability as a “party to an offence” is one of the most intricate areas of criminal law. Many are unaware that guilt can be established against those who did not commit any offence by their own hand; sometimes even by those who were not even present at the scene of the crime. Similarly, merely being present when a crime is committed does not automatically give rise to criminal liability. As such, choosing experienced and capable legal counsel is critical to protecting your legal rights and defending allegations made by the state alleging involvement as a “party”.

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