nThe Due Process Clauses of the Fifth and Fourteenth Amendments also provide important constraints on the substantive criminal law.
nDue process requires, among other things, that criminal statutes be written in such a way that a person of ordinary intelligence has a reasonable opportunity to know what is prohibited.
nAs the Supreme Court observed in 1948, “Legislation may run afoul of the Due Process Clause because it fails
to give adequate guidance to those
who would be law-abiding, to
advise defendants of the nature of the offense with which they are charged, or to guide courts in trying those who are accused.”
nWhen legislatures fail to meet this obligation, they
have succumbed to the vice of vagueness.