U.S. Supreme Court Denies Review of Arizona Case That Could Overturn 25 Death Sentences

In a deci­sion that could affect an esti­mat­ed 25 Arizona death penal­ty cas­es, the U.S. Supreme Court has denied Arizona’s request to review a fed­er­al appeals court deci­sion declar­ing uncon­sti­tu­tion­al an evi­den­tiary rule that lim­it­ed the types of mit­i­gat­ing evi­dence cap­i­tal defen­dants could present in their cas­es. The rul­ing in Ryan v. McKinney let stand a 6 – 5 deci­sion of the U.S. Court of Appeals for the Ninth Circuit in December 2015 that had reversed James McKinney​’s 1993 death sen­tence because the state’s so-called ​“causal nexus” rule uncon­sti­tu­tion­al­ly exclud­ed evi­dence about McKinney’s abu­sive child­hood and post-trau­mat­ic stress disorder. 

The Court’s rul­ing could have impli­ca­tions for many of the pris­on­ers on Arizona’s death row. The causal nexus rule, which required that mit­i­gat­ing evi­dence be direct­ly linked to the crime before it could be con­sid­ered as grounds to spare a defen­dan­t’s life, had been place in Arizona from the late 1980s until 2005. 

In 1978, the Supreme Court ruled in Lockett v. Ohio that states could not bar defen­dants from pre­sent­ing mit­i­gat­ing evi­dence relat­ing to their char­ac­ter, back­ground, or record or the cir­cum­stances of the case as rea­sons to impose a life sen­tence. Four years lat­er, in Eddings v. Oklahoma, it held that states could not require that evi­dence excuse the mur­der before it could be con­sid­ered mit­i­gat­ing. Then, in 2004, in Tennard v. Dretke, it reit­er­at­ed that any require­ment that mit­i­gat­ing evi­dence have a direct causal link to the offense vio­lat­ed the Eighth Amendment. 

By deny­ing review, the Supreme Court paved the way for oth­er pris­on­ers whose sen­tenc­ing was affect­ed by the causal nexus rule to chal­lenge their death sen­tences. In a dis­sent to the Ninth Circuit deci­sion, Judge Carlos Bea wrote that the major­i­ty deci­sion, ​“calls into ques­tion every sin­gle death sen­tence imposed in Arizona between 1989 and 2005.” 

McKinney’s case will return to state court with­in 120 days for fur­ther pro­ceed­ings, accord­ing to the Arizona Attorney General’s Office. His re-sen­tenc­ing must now be done by a jury because the U.S. Supreme Court 2002 deci­sion in Ring v. Arizona end­ed the state’s prac­tice of judges impos­ing death sentences.