The Road to Atkins: Moving Towards a Categorical Exemption

One of the first dis­cus­sions of intel­lec­tu­al dis­abil­i­ty and the death penal­ty occurred in 1978 when the U.S. Supreme Court decid­ed Lockett v. Ohio (1978). The Court held that evi­dence of a defendant’s men­tal dis­abil­i­ties is admis­si­ble dur­ing the sen­tenc­ing hear­ing as a mit­i­gat­ing fac­tor. However, the rul­ing did not for­bid the exe­cu­tion of peo­ple with intellectual disability.

In 1989, the ques­tion of whether indi­vid­u­als with intel­lec­tu­al dis­abil­i­ty could be exe­cut­ed was brought before the Supreme Court in Penry v. Lynaugh (1989). The Court decid­ed that although intel­lec­tu­al dis­abil­i­ty is a fac­tor that may lessen a defendant’s cul­pa­bil­i­ty for a cap­i­tal offense, the Eighth Amendment did not pre­clude the exe­cu­tion of a per­son based on his or her intel­lec­tu­al dis­abil­i­ty alone. The Court also decid­ed that as long as a jury or judge was able to con­sid­er a defendant’s intel­lec­tu­al dis­abil­i­ty when impos­ing sen­tence, the deter­mi­na­tion of whether death is the appro­pri­ate pun­ish­ment could be made on a case-by-case basis. The Penry deci­sion was sig­nif­i­cant in two ways. First, the rul­ing affirmed that intel­lec­tu­al dis­abil­i­ty is so rel­e­vant to the lev­el of an offender’s cul­pa­bil­i­ty that states can­not refuse to allow the jury to con­sid­er it as a mit­i­gat­ing fac­tor. Second, the Court said there was, at that time, ​“insuf­fi­cient evi­dence of a nation­al con­sen­sus against exe­cut­ing [indi­vid­u­als with intel­lec­tu­al dis­abil­i­ty] con­vict­ed of cap­i­tal offens­es for [the Justices] to con­clude that it is cat­e­gor­i­cal­ly pro­hib­it­ed by the Eighth Amendment.”

Between 1989 and 2002, dis­abil­i­ty advo­ca­cy groups mobi­lized efforts to ban the exe­cu­tion of indi­vid­u­als with intel­lec­tu­al dis­abil­i­ty. Additionally, nation­al opin­ion polls indi­cat­ed lack of sup­port for exe­cut­ing indi­vid­u­als with intel­lec­tu­al dis­abil­i­ty. For exam­ple, in the late 1980s, when 71% of the pop­u­la­tion sup­port­ed the use of death penal­ty, only about 25% favored exe­cut­ing indi­vid­u­als with intel­lec­tu­al dis­abil­i­ty (Ellsworth & Gross, ​“Social Science and the Evolving Standards of Death Penalty Law,” 2008). After 18 states banned the prac­tice through leg­is­la­tion, in 2002 the Supreme Court revis­it­ed the issue in Atkins v. Virginia, over­turned Penry v. Lynaugh, and deter­mined that the ​“leg­isla­tive judg­ment reflects a much broad­er social and pro­fes­sion­al con­sen­sus” that exe­cut­ing indi­vid­u­als with intel­lec­tu­al dis­abil­i­ty was an exces­sive pun­ish­ment not in accord with our stan­dards of decency