With the transition from English law, which had common law crimes, to the new legal system under the U.S. Constitution, which prohibited "ex post facto" laws at both the federal and state level, the question was raised whether there could be common law crimes in the United States. It was settled in the case of "United States v. Hudson", which decided that federal courts had no jurisdiction to define new common law crimes, and that there must always be a (constitutional) statute defining the offense and the penalty for it.