1. The fundamental nature of the criminal offence and the difference between categories of crimes

In this session, we begin by addressing some simple questions about what is a crime in law. There is a strong doctrinal element to this: a crime is typically understood as the combination of an act (actus reus) and an element of fault (mens rea). Guilt of a crime will result from the combination of proof beyond a reasonable doubt of the actus reus and the mens rea, and the absence of a defence of excuse or justification. The actus reus and the mens rea need to be simultaneous in time. The actus reus is described in each offence and can vary considerably. One of the key questions is whether one can commit the actus reus by omission and if so when, in a context where liberal systems of law are traditionally reluctant to impose duties to act and, a fortiori, to criminalize non compliance. Mens rea requirements are by contrast sometimes implicit and at any rate less diverse (there is an almost limitless range of acts that can be pursued, but only so many generic states of mind that can attach to them). Although the criminal justice system does its best to maintain the distinction between the two, it is worth noting that psychological elements can go into defining the actus reus either as they relate to the victim's state of mind (as in sexual assault), or certain elements of knowledge that the accused himself may have (as in unlawful possession).

The required mens rea is perhaps the most sensitive issue constitutionally, as we will see. It is also an area where different broad approaches to crime can be gauged. Mens rea, for example, is typically subjective but also potentially objective. Indeed, one of the crucial distinctions in the criminal law is between offences that require a subjective mens rea (intention, knowledge, wilful blindness) and those which, increasingly, do not and are typically based on negligence. The latter reflect an evolution of the criminal justice system towards regulatory forms of criminal justice, concerned less with the protection of certain fundamental taboos than with the smooth functioning of society. We will look at the evolution of the criminal law as one focused almost exclusively on punishing "real crimes" to one increasingly policing a range of regulatory offences. Finally, there is the question of whether one may ever be guilty of a crime merely for committing the actus reus and in the absence of any fault.

In preparation for this class, you may want to flip through the Canadian criminal code to get a sense of the diversity of offences. Try to determine for each crime what the actus reus and mens rea requirement are. 

Class preparation: