Under "Ford", once a prisoner seeking a stay of execution makes a "substantial threshold showing of insanity", he must be afforded a fair hearing at which the question of his competence to be executed can be resolved. This means he must have an "opportunity to be heard" by an impartial decisionmaker. In other words, the legal determination of his competence to be executed cannot rest solely on the determination of experts, because doing so would prevent the inmate from offering evidence to rebut any expert's opinion that he was competent to be executed.