Chester v. Thaler

Issue: Whether Texas’s use of the In re Briseno factors -- under which Texas assesses mental retardation using seven factors invented by the state court that rely heavily on the facts of the crime, have no basis in scientific literature, and conflict with the nationally accepted clinical definition of mental retardation relied on in Atkins v. Virginia -- is contrary to or an unreasonable application of Atkins v. Virginia, where these non-clinical criteria depart from the national consensus definition of mental retardation, are unrelated to a reliable determination of mental retardation, and permit the execution of mentally retarded offenders.