Opinion of the Court
lenges like his. He admits that Baze and Glossip supply the controlling test in facial challenges to a State’s chosen method of execution. But he suggests that he should not have to prove an alternative method of execution in his as-applied challenge because “certain categories” of punishment are “manifestly cruel… without reference to any alternative methods.” Brief for Petitioner 41–42 (internal quotation marks omitted). He points to “‘burning at the stake, crucifixion, [and] breaking on the wheel’” as examples of “categorically” cruel methods. Ibid. And, he says, we should use this case to add to the list of “categorically” cruel methods any method that, as applied to a particular inmate, will pose a “substantial and particular risk of grave suffering” due to the inmate’s “unique medical condition.” Id., at 44.
The first problem with this argument is that it’s foreclosed by precedent. Glossip expressly held that identifying an available alternative is “a requirement of all Eighth Amendment method-of-execution claims” alleging cruel pain. 576 U. S., at ___ (slip op., at 1) (emphasis added). And just as binding as this holding is the reasoning underlying it. Distinguishing between constitutionally permissible and impermissible degrees of pain, Baze and Glossip explained, is a necessarily comparative exercise. To decide whether the State has cruelly “superadded” pain to the punishment of death isn’t something that can be accomplished by examining the State’s proposed method in a vacuum, but only by “compar[ing]” that method with a viable alternative. Glossip, 576 U. S., at ___ (slip op., at 13); see Baze, 553 U. S., at 61. As Mr. Bucklew acknowledges when speaking of facial challenges, this comparison “provides the needed metric” to measure whether the State is lawfully carrying out an execution or inflicting “gratuitous” pain. Brief for Petitioner 42–43. Yet it is that very comparison and needed metric Mr. Bucklew would now have us discard. Nor does he offer some per-
