In the case of Robert Wong, Warden v. Fernando Belmontes Jr., 2009, the U.S Supreme Court ruled in favor of Robert Wong (the warden). The issue at hand was whether or not a jury instruction during Belmontes' trial had been constitutionally inadequate because it potentially led jurors to believe they could not consider certain mitigating evidence when deciding on his sentence. This case marked the third time that Belmontes’ death penalty sentence reached the Supreme Court. In this instance, by a 5-4 vote, with Justice Kennedy writing for the majority and joined by Chief Justice Roberts and Justices Scalia, Thomas and Alito; while Justices Stevens dissented along with Souter, Ginsburg and Breyer; it was decided that there were no constitutional errors made during sentencing instructions given to jurors in his original trial.

In the dissenting opinion for Robert Wong, Warden v. Fernando Belmontes, Jr., Justice Stevens argued that the majority's decision failed to properly consider how a jury might interpret instructions given during sentencing. He contended that while jurors may have been technically permitted to consider mitigating evidence of Belmontes' potential for future good behavior in prison, they were not explicitly instructed to do so. This lack of clear instruction could lead them to disregard such evidence when deciding on a sentence. Furthermore, he criticized the majority's reliance on prior case law as precedent because those cases did not involve juries being asked to make predictions about a defendant’s future conduct based on their past actions or character traits outside of criminal activity. Finally, he expressed concern over whether this ruling would encourage prosecutors and judges in capital cases to minimize discussion of defendants’ potential for rehabilitation.