Procedural due process has the comfortable feel of an old, familiar legal doctrine. If defining the substantive standards imposed by due process can seem challenging, procedural due process seems straightforward by comparison: a person may not constitutionally be deprived of life, liberty or property by governmental action without notice and a meaningful opportunity to be heard. These core procedural rules seem indisputable. In the American adversary tradition, after all, it is commonly said that no better instrument has been devised for arriving at truth than a contest between parties, presided over by a neutral arbiter. And yet, in criminal proceedings, even procedural due process is not quite so simple. In particular, this Article ex...