The Eighth Amendment to the Constitution, applicable to the States through the Due Process Clause of the Fourteenth Amendment, see Robinson v. California, 370 U. S. 660, 666 (1962), provides that “[e]xcessive bail shall not be required, nor excessive fines imposed, nor cruel and unusual punishments inflicted.” We begin with the principle, settled by Gregg, that capital punishment is constitutional. See 428 U. S., at 177 (joint opinion of Stewart, Powell, and STEVENS, JJ.). It necessarily follows that there must be a means of carrying it out. Some risk of pain is inherent in any method of execution—no matter how humane—if only from the prospect of error in following the required procedure. It is clear, then, that the Constitution does not demand the avoidance of all risk of pain in carrying out executions.

(John G. Roberts Jr, Baze v. Rees, 553 U. S. ___ [2008] [brackets in original])