“ Unavoidably, then, the question whether such persons can be put to death once the deterioration of their faculties has rendered them unable even to appeal to the law or the compassion of the society that has condemned them is central to the administration of the death penalty in this Nation. ”

“ Like the District Court, the Court of Appeals concluded that petitioner's inability to recognize or communicate facts that might make his punishment unlawful or unjust was of no legal consequence. See 923 F.2d, at 572-573. Purporting to draw on the majority opinion in Ford and on Justice Powell's concurring opinion, the Court of Appeals concluded that the only considerations relevant to petitioner's competency were " (1) whether petitioner understands that he is to be punished by execution; and (2) whether petitioner understands why he is being punished." ”

“ For if a prisoner is incapable of recognizing or communicating facts that would facilitate collateral review, there is no reason to assume that collateral review in his case has rooted out all trial errors. ”