Constitutional Retroactivity in Criminal Procedure

The “watershed” doctrine gives prisoners a constitutional basis to reopen their cases based on a new due process protection that would have made a difference had it been announced before their appeals were exhausted. The Supreme Court has imposed nearly impossible conditions, however, for any new rule of criminal procedure to apply retroactively to any final conviction or sentence. No such rule can be backdated unless it enhances not only the accuracy of criminal verdicts, but also “our very understanding of the bedrock” tenets of fairness in criminal trials. Rules that satisfy both these requirements, the Court calls “watersheds.” In the quarter-century since it established this doctrine the Court has unequivocally denied accuracy-and-fairness credentials to every one among the dozens of new procedural rules whose watershed status it has considered. Scholarly consensus accordingly casts watershed doctrine as exceptional, esoteric, and insignificant. \nThis Essay challenges that consensus. We use the dynamic concentration model of game theory to show how watershed doctrine counteracts the structural undersupply of constitutional due process rules. The Court maintains too small a caseload to scrutinize more than a fraction of due process violations or specify each of its demands. This equips it poorly to rein in the punitive tendencies of elected state judges who owe their jobs to voters who tend to value crime prevention more than defendants’ rights. Watershed doctrine mitigates this enforcement problem by creating an extreme, if low-probability, threat of repealing scores of final convictions. By issuing a single new watershed rule, the Court can mandate sweeping retrials or release of prisoners into the public. This existential threat motivates state courts to insulate their states’ criminal procedures against Supreme Court incursions. To achieve the desired insulation, state courts create constitutional safe harbors by trying to align their procedures with watersheds they project the Court might announce in the future. Confirmation of this theory comes from our comprehensive study of all 358 watershed decisions state courts have issued since 1989, more than one in nine of which demonstrably inflates the retroactivity rights of criminal defendants.