In the case of Amadeo v. Zant, 1987, the US Supreme Court ruled in favor of a death row inmate who claimed that his constitutional rights were violated during jury selection for his trial. The petitioner, Tony Amadeo was convicted and sentenced to death by a Georgia court for murder. However, it was later discovered that there had been systematic exclusion of African-Americans from juries due to an unwritten policy implemented by Putnam County officials at the time of Amadeo's trial. Despite this evidence being presented after state proceedings had concluded and despite procedural default rules which would normally prevent such claims from being heard on federal habeas review, the Supreme Court held that these circumstances constituted "cause" sufficient to overcome procedural default because they affected fundamental fairness in violation of Due Process Clause under Fourteenth Amendment.

In the dissenting opinion for Amadeo v. Zant, Justice Powell argued that there was no evidence to suggest that the jury selection process in this case had been influenced by racial bias. He pointed out that while it is true that a clerk had manipulated the lists of potential jurors to reduce black representation, there was no proof presented at trial showing this manipulation affected Amadeo's specific case. Furthermore, he noted that even if such evidence existed, it would not necessarily mean Amadeo's conviction should be overturned because any error could have been harmless beyond reasonable doubt - a standard established in previous Supreme Court rulings on similar issues. In conclusion, Justice Powell believed the majority erred in its decision and did not provide sufficient grounds for granting habeas corpus relief.