In Rivas-Villegas v. Cortesluna, the Supreme Court held that a state court’s decision to deny an alien's motion for postconviction relief was not barred by the doctrine of noninquiry. The petitioner had argued that his plea agreement should have been vacated because he did not understand its terms due to language barriers and ineffective assistance of counsel. However, the Supreme Court found that there were no constitutional violations in this case and thus declined to review it under their limited jurisdiction over habeas corpus petitions from state courts. This ruling reaffirms the principle that federal courts must defer to state court decisions unless they involve a violation of federal law or are otherwise unconstitutional in nature.

In the case of Rivas-Villegas v. Cortesluna, the Supreme Court was asked to decide whether a state court’s decision to deny a motion to suppress evidence obtained in a search of a vehicle was correct. The majority opinion held that the state court’s decision was correct and that the search was reasonable under the Fourth Amendment. Justice Sotomayor, however, wrote a dissenting opinion in which she argued that the majority opinion was wrong and that the search was not reasonable under the Fourth Amendment. She argued that the search was not based on any reasonable suspicion that the vehicle contained evidence of a crime, and that the search was conducted without a warrant. She argued that the search was an unreasonable intrusion into the privacy of the vehicle’s occupants and that the evidence obtained should have been suppressed. She concluded that the state court’s decision to deny the motion to suppress was wrong and should be reversed.