P was convicted on two counts of sexual conduct with a minor under the age of 15. The prosecution introduced a videotaped forensic interview with the victim, P's 11-year-old stepdaughter. It also put in evidence the victim's nightgown, with traces of P's DNA. P introduced evidence of the victim's recantations, including testimony from the victim's grandmother and mother and a second videotaped interview in which the victim denied any abuse. The victim also denied any abuse when she testified at trial. A prosecution expert testified that recantations of child-abuse accusations are caused often by reluctance on the part of the victim's mother to lend support to the child's claims. The jury convicted P. He was sentenced to two consecutive terms of life imprisonment with no possibility of parole for 35 years. D appointed a new attorney to represent P in his direct appeal. Arizona law did not permit her to argue on direct appeal that trial counsel was ineffective. Arizona requires claims of ineffective assistance at trial to be reserved for state collateral proceedings. While P's direct appeal was pending, the attorney began a state collateral proceeding by filing a 'Notice of Post-Conviction Relief.' Counsel made no claim trial counsel was ineffective and later filed a statement asserting she could find no colorable claims at all. P alleged that he was unaware of the ongoing collateral proceedings and that counsel failed to advise him of the need to file a pro se petition to preserve his rights. The state trial court dismissed the action for postconviction relief. On federal habeas review, and with new counsel, P sought to argue he had received ineffective assistance of counsel at trial and in the first phase of his state collateral proceeding. P claimed his trial counsel had been ineffective for failing to challenge the prosecution's evidence. P's trial counsel should have objected to the expert testimony explaining the victim's recantations or should have called an expert witness in rebuttal. P also faulted trial counsel for not pursuing an exculpatory explanation for the DNA on the nightgown. Because the state collateral proceeding was the first place to challenge his conviction on grounds of ineffective assistance, P maintained he had a constitutional right to an effective attorney in the collateral proceeding. The question is whether a federal habeas court may excuse procedural default of an ineffective assistance claim when the claim was not properly presented in state court due to an attorney's errors in an initial-review collateral proceeding. The Arizona Court of Appeals denied P relief because he failed to raise his claims in the first collateral proceeding. P then filed a petition for a writ of habeas corpus, again raising the ineffective assistance of trial counsel claims. P acknowledged the denial of his claims by relying on a well-established state procedural rule, which, under the doctrine of procedural default, would prohibit a federal court from reaching the merits of the claims. P argued because the first postconviction counsel was ineffective in failing to raise any claims in the first notice of postconviction relief and in failing to notify P of her actions he had cause to use that fact to excuse a procedural default. The District Court denied the petition because D's preclusion rule was an adequate and independent state-law ground to bar federal review. The Ninth Circuit affirmed. holding that absent a right to an attorney in a collateral proceeding, an attorney's errors in the proceeding do not establish cause for a procedural default. The Supreme Court granted certiorari.