Chase v. Mississippi

Issue: (1) Whether it violates the Eighth and Fourteenth Amendments, as understood in Atkins v. Virginia and Hall v. Florida, for a State court to refuse to accept data from clinical interviews with persons who knew a death-sentenced prisoner during the “developmental period” where the uncontested testimony and scientific and clinical consensus finds such data to be useful in determining the second criteria for intellectual disability, i.e., adaptive functioning deficits; (2) whether it violates the Eighth and Fourteenth Amendments, as understood in Atkins and Hall, for a State court to impose a requirement that a death-sentenced prisoner present “normed data” from clinical instruments in order to prove the second criteria for intellectual disability under Atkins; and (3) whether it violates the Fourteenth Amendment Due Process Clause for a State court to create a novel requirement that a death-sentenced prisoner present “normed data” from clinical instruments in order to prove the second criteria for intellectual disability under Atkins, and impose that requirement to deny relief to a prisoner who had no notice of the requirement during his evidentiary hearing.