De minimis non curat lex—the idea that the law does not concern itself with trifles—is originally a private law maxim whose applicability in criminal law is uncertain. The author argues that de minimis should not exist as a criminal defence. This article distinguishes the use of de minimis as an (accepted) interpretative principle in criminal law from its application as a defence. In doing so, the author critiques the potential rationales for de minimis offered by Arbour J in Canadian Foundation for Children, Youth and the Law v Canada (Attorney General). Instead, the author draws a parallel between de minimis and constitutional exemptions, arguing that they are functionally identical. As the Supreme Court of Canada has rejected constitutional exemptions as a remedy, it should also reject de minimis as a defence. The author also notes that judges are responsible for adjudicating innocence and guilt, not deciding whether the criminal justice system should be invoked—judges should not have the power to override prosecutorial discretion by invoking de minimis.