The Eighth Amendment does not categorically prohibit execution of intellectually disabled individuals; states may define intellectual disability for capital punishment but must consider all relevant evidence, including standard error of measurement.

The question presented is whether the Eighth Amendment bars execution of a person with intellectual disability when multiple IQ scores exceed 70 but fall within the standard error of measurement. The Eighth Amendment provides: 'Excessive bail shall not be required, nor excessive fines imposed, nor cruel and unusual punishments inflicted.' At ratification, 'cruel and unusual' referred to punishments that were barbaric, torturous, or disproportionate in method—not to the mental state of the offender. The common law allowed execution of persons with mental disabilities if they were competent to understand the punishment and assist in their defense. There was no categorical exemption for intellectual disability. The phrase 'unusual' also meant contrary to long usage or not authorized by law; executing a competent person with low IQ was not considered unusual. Therefore, the Eighth Amendment does not categorically prohibit execution of intellectually disabled individuals. Instead, the determination of intellectual disability for capital punishment is a matter of state law, subject to the requirement that the punishment not be disproportionate to the crime or the defendant's culpability. States may adopt definitions of intellectual disability, but they must consider all relevant evidence, including multiple IQ scores and the standard error of measurement. The judgment of the Eleventh Circuit is reversed, and the case is remanded for further proceedings consistent with this opinion. Atkins v. Virginia and its progeny are overruled as inconsistent with the original meaning of the Eighth Amendment.