Buck's lawyers were not challenging his conviction, but were seeking another chance to argue that he should not get the death penalty.
The Supreme Court ruled in 6–2 decision that Buck received ineffective assistance of counsel in violation of the Sixth Amendment, and allowing him to appeal his capital sentence. Justices Clarence Thomas and Samuel Alito dissented.
Chief Justice Roberts wrote for the majority stating:
“Dr. Quijano’s testimony appealed to a powerful racial stereotype—that of black men as “violence prone.” In combination with the substance of the jury’s inquiry, this created something of a perfect storm. Dr. Quijano’s opinion coincided precisely with a particularly noxious strain of racial prejudice, which itself coincided precisely with the central question at sentencing. The effect of this unusual confluence of factors was to provide support for making a decision on life or death on the basis of race. …
[T]his is a disturbing departure from a basic premise of our criminal justice system: Our law punishes people for what they do, not who they are. Dispensing punishment on the basis of an immutable characteristic flatly contravenes this guiding principle.”
Buck is now eligible for a new sentencing hearing or his sentence will be changed to life in prison.