Gonzales, the nation's highest legal officer, has been point man for serial assaults against the rule of law, most recently in the crude attempt to politicize criminal prosecutions. Obstruction of a prosecution is a felony, even when committed by the attorney general.

The firings of U.S. attorneys had multiple political motives, all contrary to longstanding practice. In some cases, Republican politicians and the White House were angry that prosecutors were not going after Democrats with sufficient zeal. In other cases, they wanted the prosecutors to lighten up on Republicans. In still others, exemplary prosecutors were shoved aside to make room for rising Republican politicians being groomed for higher office.

It's hard to imagine a more direct assault on the impartiality of the law or the professionalism of the criminal justice system. There are several other reasons to remove Gonzales, all involving his cavalier contempt for courts and the liberties of citizens, most recently in the FBI's more than 3,000 cases of illegal snooping on Americans.

Why impeachment? In our system of checks and balances, the Senate confirms members of the Cabinet, but impeachment for cause is the only way to remove them. The White House, by refusing to cooperate, has now left Congress no other recourse.

Instead of responding to lawful subpoenas, President Bush has invited congressional leaders to meet informally with Karl Rove and other officials involved in the prosecutor firings, with no sworn testimony and no transcript. Rove narrowly escaped a perjury indictment in the Cheney/Libby/Wilson affair. You might think these people had something to hide.

After the administration refused to cooperate, Republican Senator Arlen Specter inadvertently gave the best rationale for impeachment. Referring to the White House invocation of executive privilege, Specter warned, "If there is to be a confrontation, it's going to take two years or more to get it resolved in court."

Exactly so. By contrast, an impeachment inquiry could be completed in a matter of months. The White House, knowing the stakes, would find it much harder to stonewall. And Gonzales might well be asked to resign rather than exposing the administration to more possible evidence of illegality.

In refusing to cooperate, Bush puffed himself up to the swaggering truculence that has worn so thin, declaring, "We will not cooperate with a partisan fishing expedition." But this investigation is hardly partisan, since several Republican senators and congressmen have already called for Gonzales to resign. And if there were ever a legitimate subject of full congressional investigation, tampering with criminal investigations on political grounds is surely one.

As for fishing expeditions, compared with what? The Whitewater investigation ended with no charges related to the original investigation and veered instead into sexual exposé -- which had what connection with Whitewater, remind me? -- now there was a partisan fishing expedition.

But can the House impeach the attorney general? The Constitution is clear that Congress may impeach "all civil officers of the United States." In our history, the House has impeached two presidents, Andrew Johnson and Bill Clinton -- Nixon resigned as the House was preparing a formal vote -- and just one member of the cabinet, William Belknap, secretary of war under president Ulysses S. Grant.

Belknap had profited from kickbacks by military contractors. The House began impeachment proceedings, documented the charges, and just before the articles were formally voted, on March 2, 1876, Belknap resigned. But the House voted impeachment anyway. The reason, as House Judiciary Chairman J. Proctor Knott explained to the Senate, "was that his infamy might be rendered conspicuous, historic, eternal, in order to prevent the occurrence of like offenses in the future."

Knott, who managed the Belknap impeachment proceedings for the House, might have been speaking of Gonzales … or Rumsfeld … or Cheney.

A fine discussion of the Belknap precedent was written last December on the legal website FindLaw.com, by, of all people, President Nixon's former legal counsel John Dean. (Astoundingly, the best lawyer the Bush White House can find for advice on stonewalling is another Watergate veteran, Fred Fielding.)

And speaking of Nixon, there's another reason to impeach Gonzales. Though the assaults on the Constitution by Bush and Cheney surely rise to impeachable offenses, the Democratic leadership has been loath to use the impeachment process. The fear is that partisan polarization, so close to the end of Bush's term, would overshadow the issues.

But now, the offenses of a Cabinet member criticized by both parties, and the stonewalling by the White House, have given ample justification. It's time for an impeachment, not just to oust Gonzales, but as a salutary warning to his superiors.

Robert Kuttner is co-editor of The American Prospect. A version of this column originally appeared in the Boston Globe.

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