McKinney v. Ryan

A sentencer in a capital case may not refuse to consider, as a matter of law, any relevant mitigating evidence offered by the defendant, including nonstatutory mitigating factors not causally connected to the crime.

James McKinney was sentenced to death, despite the submission of evidence of post-traumatic stress disorder (PTSD). The trial judge used the “causal nexus” test, and held that McKinney’s PTSD diagnosis was not causally connected to his criminal behavior, giving it no weight as a mitigating factor. McKinney filed for state post-conviction relief. His petition was denied and the Arizona Supreme Court affirmed, holding that McKinney’s PTSD had no causal nexus to his crimes, and therefore could not be considered as a nonstatutory mitigating factor. A three-judge panel affirmed. On appeal, the Ninth Circuit then granted a rehearing en banc. The panel held that the Arizona Supreme Court unconstitutionally applied the “causal nexus” test when determining whether to consider McKinney’s PTSD as a mitigating factor, contrary to clearly established federal law in Eddings v. Oklahoma. In Eddings the Supreme Court held that a sentencer in a capital case may not “refuse to consider, as a matter of law, any relevant mitigating evidence” offered by the defendant. Arizona law provided for two types of mitigating factors: statutory and nonstatutory, such as a difficult family background or a mental condition. The panel held that the Arizona Supreme Court ruling was unconstitutional because they failed to adequately apply the “causal nexus” test for nonstatutory mitigation factors which prohibited giving weight to evidence of family background or mental condition unless it was causally connected to the crime. The panel further held that the error at issue in McKinney’s case had a substantial and injurious effect on McKinney’s sentence. The Court held that PTSD is mitigating evidence under Eddings, and the refusal to give it weight required resentencing. REVERSE and REMAND.