In the case of Betty Mitchell, Warden v. Gregory Esparza in 2003, the U.S Supreme Court ruled that federal courts should defer to state court decisions on matters of law and fact unless those decisions are unreasonable. The case involved Gregory Esparza who was convicted for murder in Ohio State court and sentenced to death. He appealed his sentence claiming ineffective assistance of counsel because his lawyer failed to present mitigating evidence during sentencing phase. His appeal was denied by both state post-conviction courts and federal district court but granted by Sixth Circuit Court which held that state courts unreasonably applied clearly established Federal Law as determined by Supreme Court regarding effective assistance of counsel claim. The Supreme Court reversed this decision stating that under Antiterrorism and Effective Death Penalty Act (AEDPA), a federal habeas corpus relief may not be granted with respect to any claim adjudicated on merits in State court proceedings unless it resulted in decision contrary or involving an unreasonable application of clearly established Federal law as determined by Supreme Court or based on an unreasonable determination of facts considering evidence presented at State trial proceeding.

In the dissenting opinion for Betty Mitchell, Warden v. Gregory Esparza, Justice Scalia argued that the majority's decision was a departure from established precedent and an overreach of federal authority into state court decisions. He contended that the Antiterrorism and Effective Death Penalty Act (AEDPA) required deference to state courts unless their rulings were contrary to or involved an unreasonable application of clearly established Federal law as determined by Supreme Court precedents. In this case, he believed there was no such contradiction or unreasonableness in Ohio’s death penalty sentencing scheme which allowed judges rather than juries to determine whether aggravating circumstances outweighed mitigating factors in capital cases. The majority had ruled this unconstitutional based on Apprendi v New Jersey (2000), but Scalia pointed out that Apprendi did not involve a death sentence nor explicitly address it; thus its principles could not be directly applied here without further clarification from future cases.