When a state court issues a reasoned merits decision on only one component of a multi-component claim, does AEDPA require federal habeas courts to defer to the state court's ruling or conduct de novo review on the unaddressed component?

The Antiterrorism and Effective Death Penalty Act prohibits federal habeas corpus relief on any claim that was adjudicated on the merits in state court, unless that adjudication contradict ed or unreasonably applie d clearly established federal law or unreasonably determined the facts. See 28 U.S.C. § 2254(d). The question presented is: When the last state court to review a petitioner’s claim issues a reasoned merits decision —but only on a single component of a multiple -component claim , such as the performance or prejudice prong of a claim under Strickland v. Washington , 466 U.S. 668 (1984) —does AEDPA require that a federal habeas court defer to a lower state court’s earlier ruling on the other component as the Third and Fifth Circuits have held, or should the federal court conduct de novo review on that component as the Seventh, Ninth, and Eleventh Circuits have held?