BYGONES…. Barack Obama noted the other day that he believes the nation should “look forward as opposed to looking backwards.” The comment came in response to a question about investigating alleged crimes committed by the Bush administration.

I should note that I can understand exactly why the incoming president feels this way. If I were in his shoes, I’d be inclined to think the same thing. Obama is taking office facing the kind of challenges and crises few presidents have had to endure — economic collapse, Iraq, Afghanistan, global warming, the list goes on — and it will take all of his energies, and more than a little luck, to succeed. The incoming president’s to-do list is daunting to the point of being overwhelming.

In this context, investing time and political capital in prosecuting the last administration hardly seems appealing. Obama wants to “turn the page” on the last eight years, not study the page for evidence of possible crimes.

But Paul Krugman argues today that Obama can’t just turn a blind eye to Bush-era wrongdoing, even if it would be politically convenient to do so.

Now, it’s true that a serious investigation of Bush-era abuses would make Washington an uncomfortable place, both for those who abused power and those who acted as their enablers or apologists. And these people have a lot of friends. But the price of protecting their comfort would be high: If we whitewash the abuses of the past eight years, we’ll guarantee that they will happen again.

Meanwhile, about Mr. Obama: while it’s probably in his short-term political interests to forgive and forget, next week he’s going to swear to “preserve, protect, and defend the Constitution of the United States.” That’s not a conditional oath to be honored only when it’s convenient.

And to protect and defend the Constitution, a president must do more than obey the Constitution himself; he must hold those who violate the Constitution accountable. So Mr. Obama should reconsider his apparent decision to let the previous administration get away with crime. Consequences aside, that’s not a decision he has the right to make.

Congressional Republicans would no doubt label any investigation a “partisan witch hunt.” The media would accuse Obama of “dwelling on the past,” in the midst of ongoing crises. I haven’t seen any recent polling on the subject, but it’s possible the public doesn’t have an appetite for such an inquiry, either.

But there’s that inconvenient reality that’s hard to overcome: the Bush administration appears to have broken some laws, and we’re not just talking about jay-walking-level wrongdoing.

The rule of law took a very serious hit over the last eight years. We, as a nation, can’t make things right going forward by ignoring the crimes of the recent past. If all future presidents are led to believe their criminal wrongdoing won’t matter, what incentive will they have to honor the law?

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.