Federalism and Constitutional Criminal Law

A vast body of constitutional law regulates the way that police investigate crimes and the way that criminal cases are handled at trial. The Supreme Court has imposed far fewer rules regarding what can be a crime in the first place, how it must be defined, and how much it can be punished. What explains this one-sided favoring of “procedure” over “substance?” This Article aims to unearth and assess the justification that the Court itself most often uses when it refuses to place constitutional limits on substantive criminal law: federalism. While the Court often invokes the concept to rationalize its restraint, this Article argues that federalism is not a universally effective argument against the imposition of these types of constitutional limits. Instead, different variants of “federalism” vary in their strength when used to resist different types of constitutional rules, and often the federalism-based argument is unjustified.