A more thorough explanation:

Death row is a section of a prison where prisoners who have been sentenced to death are held until their execution. It is not considered unconstitutional for prisoners to spend an extended amount of time on death row.

John was sentenced to death for his crimes and was placed on death row. He spent 20 years waiting for his execution, but his lawyers argued that this violated his Eighth Amendment rights. However, the Supreme Court has consistently denied certiorari in cases where prisoners claim that an extended stay on death row is unconstitutional.

For example, in Lackey v. Texas, the Supreme Court denied certiorari to a defendant who claimed his 17 years on death row violated the Eighth Amendment. The Court has continued to deny certiorari in subsequent cases, including Foster v. Florida (27 years on death row), Knight v. Florida (19 years on death row), and Valle v. Florida (33 years on death row).

Lower federal courts have also held that an extended stay on death row does not violate the Eighth Amendment. For instance, in Smith v. Mahoney, the Ninth Circuit held that 25 years on death row did not violate the Eighth Amendment. Similarly, in Reed v. Quarterman, the Fifth Circuit held that a 24-year delay in execution did not violate the Eighth Amendment. And in Thompson v. Sec'y for the Dep't of Corr., the Eleventh Circuit held that 31 years on death row did not violate the Eighth Amendment.

These examples illustrate that an extended stay on death row is not considered unconstitutional, despite the potential for a lengthy wait before execution.