http://www.slate.com/articles/news_and_politics/jurisprudence/2015/06/clarence_thomas_opinion_in_brumfield_v_cain_has_he_forgotten_he_s_a_supreme.html

Many people who come before the Supreme Court ask the justices to do something huge: devastate the Affordable Care Act, for instance, or declare a constitutional right to same-sex marriage. Kevan Brumfield just wanted a hearing. When Brumfield was convicted for the murder of Louisiana police officer Betty Smothers, the court still permitted states to execute mentally disabled people. In 2002’s Atkins v. Virginia, the court ruled that subjecting such people to capital punishment qualified as unconstitutional “cruel and unusual punishment.” Brumfield, who was sentenced to death, simply argued that he deserved an opportunity to prove in court that he is mentally challenged.