Criminal law defences are sometimes classified as excuses or justifications. A defence that excuses a crime is one that acknowledges the wrongfulness of the action but holds that in the circumstances the accused should not be punished for the crime. The Supreme Court has stated that excuses rest on a realistic assessment of human weakness, recognizing that a liberal and humane criminal law cannot hold people to the strict obedience of laws in emergency situations where normal human instincts, whether of self-preservation or altruism, overwhelmingly impel disobedience . . . . Praise is indeed not bestowed, but pardon is, when one does a wrongful act under pressure which . . . "over-strains human nature and no one could withstand . . . . At the heart of [necessity conceptualized as an excuse] is the perceived injustice of punishing violations of the law in circumstances in which the person has no other viable or reasonable choice available; the act was wrong but it is excused because it was unavoidable."8In other words, "excuses absolve the accused of personal accountability by focussing, not on the wrongful act, but on the circumstances of the act and the accused’s personal capacity to avoid it." Because the accused has no realistic choice but to commit the crime, "criminal attribution points not to the accused but to the exigent circumstances facing him."9Section 17 of the Criminal Code provides that a person
who commits a crime under duress from threats is "excused" from the commission of crimes.
In contrast, a defence that acts as a justification "challenges the wrongfulness of an action which technically constitutes a crime." The accused is not punished because, in the circumstances, "the values of society, indeed of the criminal law itself, are better promoted by disobeying a given statute than by observing it."10A justification is not conceived as a concession to normal human weakness. Most would classify self-defence as a justification on the basis that people have rights to defend their persons and their property. Indeed, until very recently the Criminal Code specifically stated that an accused who acts in self-defence or defence of property was "justified" in committing offences and in some cases the concept of justification was used as a reason to restrict the defence.11
As will be seen in the case of necessity and duress, whether a de-fence is conceptualized as an excuse or a justification can have a practical effect on its availability. Excuses are inherently limited by what is thought necessary for a realistic concession to reasonable human weaknesses whereas justifications are more wide-ranging in holding that certain values are so important that they justify disobeying the law. In addition, the Supreme Court has accepted the idea that a conviction of a person who committed a crime in a morally involuntary manner because the circumstances were so exigent that there was no realistic choice but to commit the crime would offend section 7 of the Charter. This acceptance is largely based on the self-defining and self-limiting nature of the juristic category of an excuse.12Nevertheless, the classification of a defence as an excuse or a justification does not affect the disposition of the accused. Duress and necessity are commonly seen as excuses, yet they lead to a complete acquittal just as the justification of self-defence does.
The distinction between excuses and justifications can be become blurred in some circumstances. A proportional relation between the harm inflicted by the accused and the harm avoided is commonly thought to be one of the defining features of a justification that makes an act taken, for example, in proportionate self-defence to be rightful. As will be seen, however, Canadian courts and legislatures have imposed proportionality requirements as part of necessity and duress
defences, even though they are commonly seen as excuses. Recent reforms to self-defence and defence of property have dropped the language of justification that previously appeared in the Criminal Code perhaps in recognition that...