In the case of McKoy v. North Carolina, the U.S Supreme Court ruled that a state cannot require jurors to unanimously agree on specific mitigating circumstances in order to consider them during sentencing in capital cases. The defendant, James Tyrone McKoy had been convicted of first-degree murder and sentenced to death by a jury who were instructed they must unanimously find any mitigating factors before considering them for his sentence. The court held this instruction was unconstitutional as it violated the Eighth Amendment's prohibition against cruel and unusual punishment and Fourteenth Amendment's due process clause because it limited individual juror consideration of relevant mitigating evidence about the defendant’s character or record or circumstances surrounding his offense which could warrant a lesser penalty than death.

In the dissenting opinion for McKoy v. North Carolina, Justice Scalia argued that the majority's decision was inconsistent with historical precedent and common law principles. He contended that unanimity in jury verdicts is a fundamental aspect of our legal system, and allowing individual jurors to disregard this principle undermines its integrity. Furthermore, he disagreed with the majority's interpretation of the Eighth Amendment, arguing that it does not require jurors to consider mitigating circumstances individually rather than as a group. He also criticized their reliance on Lockett v. Ohio and Eddings v. Oklahoma because those cases did not directly address whether unanimity is required when considering mitigating factors during sentencing in capital punishment cases.