In the case of Dora B. Schriro, Director, Arizona Department of Corrections v. Robert Douglas Smith in 2005, the U.S Supreme Court ruled that a defendant does not have to be mentally competent during post-conviction proceedings under federal law. The court held that there is no constitutional right to competence in such proceedings because they are civil in nature and do not affect an individual's liberty interest directly like criminal trials do. This decision was based on the fact that these procedures only determine whether previous legal processes were conducted fairly and correctly rather than determining guilt or innocence. Therefore, mental competency is not required for defendants during this stage of judicial review.

In the dissenting opinion for Schriro v. Smith, Justice Stevens argued that the majority's decision to deny Robert Douglas Smith a competency hearing was unjust and inconsistent with previous rulings. He contended that there were significant questions about Smith's mental health which should have been addressed in a court of law before his execution could proceed. Furthermore, he criticized the majority for ignoring established precedent on this issue, particularly Ford v. Wainwright (1986), where it was ruled unconstitutional to execute an insane person without first holding a competency hearing. Justice Stevens also expressed concern over Arizona’s failure to provide any procedural safeguards against executing mentally incompetent individuals and believed this case presented an opportunity for the Court to rectify such shortcomings in state procedures.