NEW YORK -- To choose the most bewildering action of George W. Bush since he became U.S. president in 2001 is tough. Is it starting a war without cause? Is it creating a dubious court and prosecuting a man for mass killings while committing even greater mass killings? Or is it concocting legislation that banishes habeas corpus, legalizes torture by Americans, and decriminalizes it retroactively?

This last, of course, is the Military Commissions Act, which Bush signed into law Oct. 17. It is an attempt to annul the Supreme Court's first important rebuke to his conduct of war, Hamdan v. Rumsfeld, that found the military commission set up in Guantanamo Bay in violation of the Uniform Code of Military Justice and Common Article 3 of the Third Geneva Convention. That the majorities in Congress approved of such an act long after the torture and murders at Abu Ghraib came to light demonstrates the vacuity of the talk of America losing "the moral high ground" that became fashionable just about that time.

Not that the United States has had any such grounds for much of its 230-year history. What it has had are sparkling expressions of principles from time to time that continue to give us hope, however faint. Justice Paul Stevens, who wrote the main part of Hamdan v. Rumsfeld, has reminded us of this by bringing up Yamashita v. Styer. That Supreme Court decision 60 years ago is famous for affirming the constitutionality of a military commission trying and sentencing to death a Japanese general for "failing to prevent troops under his command from committing atrocities." But it is equally famous for provoking, as Stevens put it, "an unusually long and vociferous critique" from two justices, Frank Murphy and Wiley Blount Rutledge. Reading those dissenters' opinions brings us to a different world.