Schriro v. Summerlin, 542 U.S. 348 (2004), was a case in which the United States Supreme Court held that a requirement that a different Supreme Court decision requiring the jury rather than the judge to find aggravating factors would not be applied retroactively.

[2] In April 1981, Warren Wesley Summerlin killed a creditor who had come to his home in Phoenix, Arizona, to inquire about a debt.

Under Arizona law at the time, a jury decided the question of guilt but a judge sitting without a jury decided the question of penalty after receiving evidence regarding aggravating and mitigating factors.

While the appeal in his habeas corpus case was pending in the Ninth Circuit, the Supreme Court decided Ring v. Arizona,[1] which held that such aggravating factors had to be proved to a jury rather than a judge.

The Court, in an opinion by Justice Scalia, reversed the decision of the Ninth Circuit Court of Appeals, and stated that "we give retroactive effect to only a small set of 'watershed rules of criminal procedure implementing the fundamental fairness and accuracy of the criminal proceeding.'