Liptak cites dictum from a 1993 decision, Herrera v. Collins, in which Chief Justice William H. Rehnquist
wrote for the court,» [W] e may assume, for the sake
of argument in deciding this case, that in a capital case a truly persuasive demonstration
of «
actual innocence» made after trial would render the execution
of a defendant unconstitutional and warrant federal habeas relief.»