The attorney general of the United States must be a defender of our constitutional rights. Because President Bush thinks he can do whatever he wants to do in the name of fighting terrorism, we need an attorney general who can explain to the president what the Constitution of this country is all about. We need an attorney general who does not believe the president has unlimited power. We need an attorney general who will tell President Bush that he is not above the law. We need an attorney general who clearly understands the separation of powers inherent in our Constitution. Regretfully, I have concluded that Michael B Mukasey would not be that kind of attorney general. That is why I will be voting against his nomination.

Let me be clear. Of course the United States government must do everything that it can to protect the American people from the dangerous threat of terrorism, but we can do that in ways that are effective and consistent with the Constitution and the civil liberties it guarantees. The Bush administration and the lawyers who have enabled it for the past seven years cannot be bothered with such technical legal niceties as the Bill of Rights. This administration thinks it can eavesdrop on telephone conversations without warrants, suspend due process for people classified as enemy combatants and thumb its nose when Congress exercises its oversight responsibility. That is why I called on Alberto Gonzales to resign. I had hoped that the confirmation process for a new attorney general would give the president and the Senate an important opportunity to refocus on the core American principles embedded in our Constitution.

Unfortunately, Judge Mukasey doesn't get it. At his two-day confirmation hearing before the Senate Judiciary Committee, he suggested that eavesdropping without warrants and using "enhanced" interrogation techniques for terrorism suspects might be constitutional, even if they exceeded what the law technically allowed. He said Congress might not have the power to stop the president from conducting some surveillance without warrants. He even, incredibly, claimed to be unfamiliar with the technique known as waterboarding.

Waterboarding is a "very exquisite torture," according to no less of an authority than Senator John McCain of Arizona, a former prisoner of war. Senator Sheldon Whitehouse of Rhode Island, a member of the Senate Judiciary Committee, provided Murkasey a graphic description of the practice. He told the nominee that it ''is the practice of putting somebody in a reclining position, strapping them down, putting cloth over their faces and pouring water over the cloth to simulate the feeling of drowning." Still, Mukasey refused to say it was tantamount to torture or to venture an opinion on whether it is constitutional. Torquemada's ghost might be smiling somewhere. I am not.

Without diminishing that issue, Mukasey's lawyerly obfuscation on the point is not the biggest or even the most basic problem I have with his nomination. There is an even more important reason why he should not become the next attorney general.

Mukasey should not be confirmed because he could not muster a simple, straightforward answer at his confirmation hearing when he was asked the simple, straightforward question: Is the president of the United States required to obey federal statutes? "That would have to depend," he weaseled, "on whether what goes outside the statute nonetheless lies within the authority of the president to defend the country."

As it happens, the Supreme Court, one of those pesky other branches of government, reaffirmed just last year that the president must comply with a valid federal statute. In a case involving military commissions, the majority even took note of the fact at the time that the Justice Department "does not argue otherwise." Mukasey evidently would argue otherwise. "If Judge Mukasey cannot say plainly that the president must obey a valid statute, he ought not to be the nation's next attorney general," wrote Jed Rubenfeld, a professor of constitutional law at Yale Law School who appeared before Judge Mukasey as a prosecutor. He's got that right.

It has become an American aphorism that ours is a government of laws, not men. We need an attorney general who understands that, so he can explain it to a president who does not.