In the case of Lockett v. Ohio, 1978, the U.S. Supreme Court ruled that a death sentence could not be imposed if mitigating factors were not considered by the jury during sentencing. The court held that it was unconstitutional for a state law to prevent consideration of these factors in capital cases as it violated the Eighth and Fourteenth Amendments' prohibition against cruel and unusual punishment and due process clause respectively. Sandra Lockett had been convicted under an Ohio statute which only allowed consideration of three specific mitigating circumstances when determining whether to impose a death penalty or life imprisonment without parole for first-degree murder convictions. The ruling emphasized that juries must be able to consider all relevant aspects about both crime and defendant before deciding on capital punishment.

In the dissenting opinion for Lockett v. Ohio, Justice Rehnquist argued that the majority's decision to strike down Ohio's death penalty statute was inconsistent with previous Supreme Court rulings. He contended that states should have discretion in determining how to weigh mitigating and aggravating factors when deciding on a sentence of capital punishment. Furthermore, he believed that it was not unconstitutional for a state law to limit the consideration of mitigating circumstances as long as it did not preclude any relevant evidence from being presented at trial. According to him, this would ensure fairness while also allowing states flexibility in their criminal justice systems. He criticized the majority’s approach as overly broad and warned against judicial overreach into matters best left to legislative bodies.