Whether the procedural-default doctrine bars a competency-based due process claim when a petitioner raises that claim for the first time on collateral review

The “conviction of an accused person while he is legally incompetent violates due process,” Pate v. Robinson , 383 U.S. 375, 378 (1966) , and thus a federal prisoner may collaterally attack his sentence on habeas review pursuant to 28 U.S.C. § 2255 by asserting that he was incompetent when tried. Under the doctrine of procedural default, federal courts generally do not entertain claims on collateral review that a petitioner did not previously raise on direct appeal, subject to some exceptions. Massaro v. United States , 538 U.S. 500, 504 (2003). The courts of appeals are entrenched in a 5-4 split on whether procedural default can apply to competency-based due process claims. The question presented is: Whether the procedural-default doctrine bars a competency-based due process claim when a petitioner raises that claim for the first time on collateral review.