With about 16 months left in his presidency, George Bush may have dodged an unnecessary fight by nominating Michael Mukasey to head the Justice Department. Unlike Alberto Gonzales, who left the department last week, Mr. Mukasey has bucked the administration and is known more for his judicial smarts than for loyalty.

Although his federal court decisions reined in some aspects of the administration’s “enemy combatant” strategy, Mr. Mukasey did rule that the president could hold U.S. citizens without charging them with a crime, a philosophy senators will want clarified before they vote on the nomination. Senators should also want to know how Mr. Mukasey would restore the department’s place as an independent agency, not one that furthers the administration’s agenda.

Mr. Mukasey is considered a conservative, but he is less likely to run into opposition from Democrats than others suggested for the post, such as former Solicitor General Theodore Olson. Bogged down in debate about the Iraq war, neither party would gain much from a long confirmation battle.

Despite his conservative credentials, Mr. Mukasey rejected some of the administration’s grabs for power. He presided over the case of Jose Padilla, the American held as an enemy combatant whom the administration alleged plotted to detonate a dirty bomb. In 2002, Judge Mukasey ruled that Mr. Padilla was entitled to a lawyer. He also ruled that the government had to provide evidence to justify Mr. Padilla’s detention and that his lawyer could examine it and contest its validity. Each ruling was challenged by the administration.

“Then-judge Mukasey was more than willing to defy the Bush administration and not be intimidated by threats that enforcing the rule of law would prevent the president from stopping terrorists,” former constitutional lawyer Glenn Greenlaw, wrote on Salon.com. “And he did so at a time when most people, including those who were natural political opponents of the president, were petrified of doing the same.”

In some instances, however, the judge’s opinions would make him ill suited to oversee the country’s legal system. He upheld the president’s right to detain American citizens without charging them with any crime, a ruling that was overturned by the appeals court.

Senators must clarify whether Mr. Mukasey would again suspend such fundamental rights before they determine if he would make an appropriate attorney general. They must also hear his strategy for rebuilding the Justice Department before deciding he is up to the job.