Biases & Vulnerabilities

Intellectual Disability

It is unconstitutional to impose the death penalty upon individuals with intellectual disability. Nevertheless, poor legal representation and onerous state evidentiary requirements still result in death sentences and executions of intellectually disabled defendants.

144

The number of individuals who have had their death sentences vacated due to intellectual disabilities since 2002.

120/​144

83% of those whose sentences were vacated were people of color.

Overview

The ques­tion of a nation­al ban on the use of cap­i­tal pun­ish­ment for those with intel­lec­tu­al dis­abil­i­ty was ini­tial­ly reject­ed by the United States Supreme Court in 1989, in part because at that time only a few states had adopt­ed leg­is­la­tion that pro­tect­ed this vul­ner­a­ble group of peo­ple from the death penal­ty. The Court found insuf­fi­cient evi­dence that soci­ety dis­ap­proved of the prac­tice. But just 13 years lat­er, there was a new con­sen­sus. Thirty states had either end­ed the use of the death penal­ty entire­ly, or had specif­i­cal­ly exempt­ed peo­ple with intel­lec­tu­al dis­abil­i­ties. In Atkins v. Virginia (2002), the Court held that was evi­dence that soci­ety no longer sup­port­ed the exe­cu­tion of peo­ple with intel­lec­tu­al dis­abil­i­ty. The Court also not­ed the spe­cial vul­ner­a­bil­i­ties of peo­ple in this group, includ­ing the risk that they would false­ly con­fess, and con­clud­ed that the tra­di­tion­al jus­ti­fi­ca­tion of deter­rence for this group was not applicable.

At Issue

The Atkins case was a sem­i­nal moment in the his­to­ry of the death penal­ty, not only because it had the poten­tial to spare the lives of many vul­ner­a­ble defen­dants, but also because the Court’s ratio­nale pro­vid­ed a blue­print for achiev­ing oth­er lim­i­ta­tions on its use. But the Court left the crit­i­cal deci­sion of deter­min­ing who had intel­lec­tu­al dis­abil­i­ty to each state — lead­ing to a patch­work of incon­sis­tent laws and prac­tices that left some peo­ple with­out the pro­tec­tion they deserved.

What DPIC Offers

DPIC traces the his­to­ry of this impor­tant rul­ing, not­ing the leg­isla­tive efforts in var­i­ous states and piv­otal cas­es. It pro­vides access to research regard­ing how many defen­dants have been found to have intel­lec­tu­al dis­abil­i­ty and removed from death row, and how states have com­plied with this ruling.

News & Developments


News

Mar 10, 2025

Georgia House of Representatives Unanimously Passes Bill to Ease Threshold to Prove Intellectual Disability Ahead of Capital Trials

On March 4, 2025, the Georgia House of Representatives, in a 172 – 0 vote, unan­i­mous­ly passed HB 123, which would pro­vide pre­tri­al hear­ings for cap­i­tal defen­dants to raise intel­lec­tu­al dis­abil­i­ty claims and would low­er the stan­dard of proof for those claims from beyond a rea­son­able doubt” to a pre­pon­der­ance of evi­dence,” in line with oth­er the oth­er 26 states that still retain the death penal­ty. The bill was orig­i­nal­ly intro­duced by Republican Representative Bill Werkheiser dur­ing Georgia’s…

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News

Feb 12, 2025

Georgia House Considers Bill to Provide Pretrial Hearings to Identify Capital Defendants with Intellectual Disability

For the third con­sec­u­tive ses­sion, the Georgia House of Representatives is review­ing a bill seek­ing to pro­vide bet­ter pro­tec­tions to cap­i­tal defen­dants with intel­lec­tu­al dis­abil­i­ties. Currently, the state requires a defen­dant to prove​“beyond a rea­son­able doubt” that they have an intel­lec­tu­al dis­abil­i­ty – the only death penal­ty state to have this unusu­al­ly high stan­dard. Introduced by a bipar­ti­san group of leg­is­la­tors on January 27, 2025, HB 123 would…

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News

Nov 04, 2024

United States Supreme Court Sends Case of Alabama Death-Sentenced Prisoner Back to 11th Circuit Court of Appeals

On November 4, 2024, the United States Supreme Courts released its order in the case of Hamm v. Smith, 604 U.S. ​_​(2024). The peti­tion for cer­tio­rari, filed by the State of Alabama last year, involved a pris­on­er named Joseph Clifton Smith whose death sen­tence was vacat­ed in 2021 after a United States dis­trict court found he had intel­lec­tu­al dis­abil­i­ty. Mr. Smith had tak­en five IQ tests, four of which placed his IQ in the low- to mid-70s, the range gen­er­al­ly accepted by…

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