In the case of Luis Mariano Martinez v. Charles L. Ryan, Director, Arizona Department of Corrections (2011), the U.S Supreme Court was asked to consider whether a procedural default in state post-conviction proceedings should bar a federal habeas court from hearing a substantial claim of ineffective assistance at trial if state law prohibits raising that claim during initial-review collateral proceedings. The petitioner, Luis Mariano Martinez, had been convicted for sexual conduct with his minor stepdaughter and sentenced to two consecutive terms of 35 years' imprisonment without possibility of parole. He argued that he received ineffective legal counsel both during his trial and in subsequent appeals processes because they failed to raise an argument about his competence at trial due to intoxication or mental illness. The Supreme Court ruled 7–2 in favor of Martinez, holding that inadequate assistance by counsel during initial-review collateral proceedings may establish cause for a defendant's procedural default on claims regarding ineffective assistance at trial under certain circumstances - specifically when state law requires such claims be raised initially in collateral rather than direct review procedures.

In the dissenting opinion for Luis Mariano Martinez v. Charles L. Ryan, Justice Scalia argued that there is no constitutional right to an effective attorney during post-conviction proceedings. He contended that ineffective assistance of counsel claims should be treated as a type of procedural default, which can only be excused if the defendant can show cause and prejudice. In this case, he believed Martinez failed to demonstrate either element adequately. Furthermore, Scalia criticized the majority's decision as creating a new constitutional rule without any basis in precedent or historical practice - essentially legislating from the bench rather than interpreting existing law faithfully.