In 1996, when Congress cracked down severely on habeas corpus petitions by prisoners who had already had one such review, it left an exception for "new rules of constitutional law, made retroactive to cases on collateral review by the Supreme Court." 28 U.S.C. § 2244(b)(2)(A). Cunningham v. California, 549 U.S. 270 (2007), which applied the Apprendi line of cases to California's three-tier system of noncapital felony sentencing, is not a new rule for this purpose, the Ninth Circuit held in Wright v. Dexter yesterday. If it were new, it wouldn't be retroactive, for the same reasons that the Supreme Court held Ring v. Arizona is not in Schriro v. Summerlin, 542 U.S. 348 (2004), but the opinion didn't mention that.

The window of prisoners who get new sentencing proceedings or reduced sentences as a result of Cunningham is small.