. . . nor be deprived of life, liberty, or property, without due process of law.
The Due Process Clause of the 5th Amendment contains some of the most important— and most famous—language in the entire Constitution. One reason for its importance and fame is that people vehemently disagree about its meaning. As Justice Frankfurter said in Joint Anti-Fascist Refugee Committee v. McGrath (1951), “‘due process,’ unlike some legal rules, is not a technical conception with a fixed content” and it “cannot be imprisoned within the treacherous limits of any formula.” Its meaning must be determined by combining elements of “history, reason, the past course of decisions, and stout confidence in the strength of the democratic faith which we profess.”
In other words, “due process of law” is one of those grand, sweeping phrases that sounds great—who could be against due process?—but which could mean many things. There are at least two major interpretations of the Due Process Clause that have uneasily coexisted since the middle of the 18th century: procedural due process and substantive due process—two interpretations with two very different meanings.