Specifically, the Court held that judges are not required to affirmatively instruct juries about the burden of proof for establishing mitigating evidence, and that joint trials of capital defendants "are often preferable when the joined defendants’ criminal conduct arises out of a single chain of events".

[12] Justice Sonia Sotomayor wrote a dissenting opinion in which she argued that the Supreme Court should not have reviewed these cases because Kansas did not violate any party's constitutional rights.

[13] She also expressed concern that the majority's opinion would discourage states from developing techniques for ensuring fair procedures during capital trials.

[14] She wrote, "I worry that cases like these prevent States from serving as necessary laboratories for experimenting with how best to guarantee defendants a fair trial".

[17] Mark Joseph Stern wrote the 8–1 vote was unexpected in light of Justice Ruth Bader Ginsburg and Justice Stephen Breyer's previous disapproval of capital punishment, and he suggested that "the court’s judgment calls into question optimistic speculation that the end of the death penalty is nigh".