WASHINGTON — Sen. Sheldon Whitehouse has no quarrel with President Obama’s declaration about the prospect of a special commission to investigate alleged wrongdoing by the Bush administration. “I’m more interested in looking forward than in looking backwards,” the president said this month at his first news conference.

Nor does Whitehouse disagree with Mr. Obama’s new attorney general, Eric Holder, who told Senate Republicans weighing his nomination to run the Justice Department that he won’t try to “criminalize policy differences.”

All the same, Whitehouse begs to differ with a proposition about the Bush era that he describes this way: “Just go back and say, ‘You know what? Those were bad days, they’re over. We don’t need to look back. We don’t need to understand that. We’re just going to go forward.’ ”

Therefore, the Rhode Island Democrat — who has won points among party colleagues for his aggressive questioning of Bush policies on warrantless wiretaps, interrogations of suspected terrorists, and the firing of federal prosecutors — strongly favors a formal examination of those issues. One possible vehicle for such a probe, according to Whitehouse, is what has become known as a “truth commission.”

Nevertheless, Whitehouse called in a recent interview for some caution in launching such probes. He also expressed a strong interest in examining the mechanisms that the Bush administration used to justify some of its policies. In particular, Whitehouse wants to scrutinize the workings of a Justice Department unit called the Office of Legal Counsel.

The Bush administration did damage that should be examined so that it can be undone and avoided in the future, he said. But if a truth commission is created to make such inquiries, its operations should be limited, he said. Certain investigations, he added, might better be conducted by other organizations.

Whitehouse applauded earlier this month when Sen. Patrick J. Leahy, D-Vt., the Judiciary Committee chairman, proposed the creation of an independent commission — with subpoena power — to investigate alleged wrongdoing by the Bush administration. Leahy has suggested a broad range of inquiry, including the use of intelligence reports to argue for an invasion of Iraq, the legal justifications for harsh interrogation techniques and warrantless wiretapping, and the firing of the U.S. Attorneys. As he noted in a speech at Georgetown University, his committee — of which Whitehouse is a member — has pushed hard on all those fronts over the past two years.

Whitehouse said in a Senate speech on June 21, “If procedures and institutions of government have been corrupted and are not put right, that past will assuredly bear on the future. In an ongoing enterprise like government, the door cannot be so conveniently closed on the closets of the past. The past always bears on the future.”

Otherwise, he said in last week’s interview, a chance is lost to learn a lesson and the past becomes “a blueprint for somebody to come back and do it all over again.”

Beyond the possibility of limiting a truth commission’s investigations, Whitehouse also said that the existing systems of criminal justice and of congressional supervision should be permitted to do their work. For example, he noted that a federal prosecutor has worked with a federal grand jury for months to investigate possible lawbreaking in the firings of U.S. Attorneys.

But Whitehouse said there is room for an open investigation of the methods that the Bush administration used to secure legal justification for such actions as waterboarding terrorist suspects — even if the harsh questioning technique is eventually outlawed as a form of torture.

“It’s important to look back because you need to defend the integrity of governmental processes that have been set up and improved over decades and when somebody takes a shortcut, when somebody finds a way to tunnel through, you’ve got to go back and figure out what they did, expose it, and that is a healthy and salutary way of preventing it from happening again,” he said.

“The simplest concern and one that merits most exploration is whether the Office of Legal Counsel gave up its independence and instead of doing what a lawyer is supposed to do — which is to give the client the best advice you can consistent with the law — instead got told what to do, possible by the office of the vice president and then backfilled its legal analysis to the predetermined conclusion.”

Whitehouse said there is a broader question about the OLC that might well be examined by a congressional panel or a truth commission. That is the possibility that the Bush White House undertook a wide-ranging effort to create a web of questionable precedents as the foundation for a claim of expanded power for the chief executive.

jmulligan@belo-dc.com