Former Supreme Court Justice Lewis Powell, the author of McCleskey v. Kemp, later admitted to a biographer that he was wrong in that decision and that he belatedly found capital punishment to be unworkable:

Too late for Warren McCleskey and numerous other executed prisoners, retired Justice Lewis Powell now concedes that he was wrong to cast the deciding fifth Supreme Court vote to uphold Mr. McCleskey’s death sentence in a major case. But it is not too late for Congress to correct the Court’s mistake and try to remove the stain of racial prejudice from the death penalty in America.

Justice Powell’s acknowledgment appears in a new biography by John Jeffries, a law professor at the University of Virginia. Asked whether he would change his vote in any of the cases that had come before him, the Justice replied: “Yes, McCleskey v. Kemp.” Indeed, he added that he now found capital punishment itself unworkable and would vote against it in any case.

“Justice Powell’s New Wisdom,” The New York Times, June 11, 1994