he was aware of the State’s rationale for executing him. In 2019, in the case of Alabama death-row prisoner Vernon Madison, the Court again addressed the proper standard for determining competency to be executed. Madison had cognitive dementia resulting from a series of strokes that, his lawyers said, left him without a rational understanding of why Alabama intended to execute him. The Alabama courts had declared him competent to be executed, ruling that Panetti applied only to cases in which prisoners understanding of the reasons for their pending execution were distorted by delusional mental illness. In Madison v. Alabama, the US Supreme Court disagreed, holding that the critical inquiry was whether the prisoner had a rational understanding of the reasons for the execution, not the type of disorder that caused him or her to lack a rational understanding. A distinct, but related, issue in the U.S. death penalty is the constitutionality of applying capital punishment to those with intellectual disability. Intellectual disability is a developmental disorder characterized by significantly subaverage intellectual functioning, substantially impaired daily functioning, and onset during the developmental period. The US Supreme Court first addressed this issue in 1989 in the case of Penry v. Lynaugh, in which Texas death-row prisoner Johnny Paul Penry argued that the application of the death penalty to individuals with mental retardation, as the disorder was then known, constituted cruel and unusual punishment in violation of the Eighth Amendment. Penry presented evidence that his that his IQ ranged from 50 to 63 — far below the 70-75 IQ level that is typically considered evidence of intellectual disability — and that he possessed the mental abilities of a six-and-a-half-year-old. The Texas state and federal courts denied Penry's challenge and, in a five-to-four decision, the US Supreme Court ruled that the Eighth Amendment did not categorically prohibit the execution of individuals with mental retardation. Following the ruling, sixteen states as well as the federal government passed legislation that banned the execution of offenders with mental retardation. The Supreme Court revisited Penry in 2002 in the case of Atkins v. Virginia. By a vote of 6-3, the Court held that the Eighth Amendment prohibition against cruel and unusual punishment applied to those with intellectual disability. The Court referred to the clinical definitions of the disorder in use by the medical community but ultimately left to the states the determination of who qualified as intellectually disabled.