That seems to be the charge Alan Dershowitz is hurling here, and picked up by the America blog In All Things:

I never thought I would live to see the day when a justice of the Supreme Court would publish the following words:

“This court has never held that the Constitution forbids the execution of a convicted defendant who has had a full and fair trial but is later able to convince a habeas court that he is ‘actually’ innocent. Quite to the contrary, we have repeatedly left that question unresolved, while expressing considerable doubt that any claim based on alleged ‘actual innocence’ is constitutionally cognizable.”

Yet these words appeared in a dissenting opinion issued by Justices Antonin Scalia and Clarence Thomas on Monday. Let us be clear precisely what this means. If a defendant were convicted, after a constitutionally unflawed trial, of murdering his wife, and then came to the Supreme Court with his very much alive wife at his side, and sought a new trial based on newly discovered evidence (namely that his wife was alive), these two justices would tell him, in effect: “Look, your wife may be alive as a matter of fact, but as a matter of constitutional law, she’s dead, and as for you, Mr. Innocent Defendant, you’re dead, too, since there is no constitutional right not to be executed merely because you’re innocent.”

It would be shocking enough for any justice of the Supreme Court to issue such a truly outrageous opinion, but it is particularly indefensible for Justices Scalia and Thomas, both of whom claim to be practicing Catholics, bound by the teaching of their church, to do moral justice. Justice Scalia has famously written, in the May 2002 issue of the conservative journal First Things, that if the Constitution compelled him to do something that was absolutely prohibited by mandatory Catholic rules, he would have no choice but to resign from the Supreme Court.

But whatever the view of the church is on executing the guilty, surely it is among the worst sins, under Catholic teaching, to kill an innocent human being intentionally. Yet that is precisely what Scalia would authorize under his skewed view of the United States Constitution. How could he possibly consider that not immoral under Catholic teachings? If it is immoral to kill an innocent fetus, how could it not be immoral to execute an innocent person?

Now, it could be argued that Dershowitz and Scalia view the law through very different lenses (and from different ends of the political spectrum, too). But Dershowitz does raise some compelling questions. You can read the rest of his essay and decide for yourself.