When (and Where) is a Crime a Crime? “Double Criminality” as a Principle of Fundamental Justice

The idea that crime crosses borders is fast becoming ordinary, even old hat, particularly in an age of online crime such as ransomware attacks, cyber-extortion and the like. As we have become more geographically mobile, however, it is increasingly common for people to have engaged in criminal conduct in one state1 but then seek to exercise legal rights, or face legal entanglements, in others. Legal questions can then arise about what effect should be given by one state—in this article, Canada—to an individual’s conduct that was, or is alleged to have been, a crime in a foreign state. The inquiry boils down to this: what should the law do in situations where one’s status as a criminal offender crosses borders, or some party or state agency seeks to have it do so? Put another way, in situations where it matters legally that a person has committed a crime, does it matter that the crime was committed in a foreign state? And if so, how do we determine whether that foreign crime should be given legal effect here in Canada?