  Whether or not mens rea should be necessary for criminal responsibility, it is rarely claimed that it should be sufficient. The widespread belief that we should not countenance thought crimes, leads most writers to claim that there should be an actus reus element to each criminal offence. Paradigmatically, this element is satisfied only if \(D\) acts in a way that causes some outcome, such as death, or property damage, or fear of violence. This paradigm does, of course, admit of a number of exceptions. As well as inchoate offences—like attempts or conspiracies—most systems of criminal law include liability for some omissions. Imagine \(D\) sees \(V\) drowning in a shallow pond and chooses to do nothing. There is no prior connection between \(D\) and \(V\). If the pond is in London, \(D\) commits no offence. Move the drama to Paris and we have ourselves a crime. As this example suggests, both academics and legal systems remain divided over the positive obligations that should be imposed by criminal law (Alexander 2002; Ashworth 2015).