There are two things to consider here, and in both of them Obama is wrong, wrong, wrong.
The first one is ducking Congressional authorization for hostilities in Libya. I've argued that it's not a Constitutional violation, nor a question of tyranny. But it is an awful choice for a president. I'm not the first one to say this, but it's pretty obvious: Obama should have gone to Congress immediately and demanded a vote, in order to give Members of Congress a political stake in the success of the mission.
What if Congress hadn't gone along? Well, that's not good for the president, but it does give him some information very much worth knowing. If Congress was so wary of the operation, for either substantive or partisan reasons, that it wouldn't authorize action, then the president is way better off knowing about it for Day 1. In such cases, perhaps the president should drop the action, or perhaps it just means he should devote additional resources to selling the plan.
Now, what of the procedural question raised by the NYT article last week by Charlie Savage: that Obama bypassed normal procedures for determining whether he was required to formally report hostilities to Congress. As Savage reports, the normal procedure when the president wants advice on the law would be to have the Office of Legal Counsel in the Justice Department collect views within the government and reach a decision; Obama, instead, treated OLC as just one of several opinions, apparently giving equal weight even to lawyers within the White House.
The president, as several people have commented, has a perfect right to do so; he's the president, and neither OLC opinions or regular procedures are binding. However, I'll agree with those who say that it's a very bad idea for Obama to operate this way.
The reason is basically very similar to the reason he should have gone to Congress in the first place. Presidents need information. Lots of information. And they are in an excellent position to be well-informed. But dangers lurk: people may only tell the president what they think he wants to hear, and the president may only choose to hear what he wants to hear.
Standard procedures involving the OLC for legal advice, then, are sensible for presidents precisely because they (should!) want to hear the truth, even when it isn't convenient for them. As Jack Goldsmith says:
This is not a process designed to produce a sound legal decision. (In the NYT story, former OLC chief Walter Dellinger makes a similar point.) When the President effectively decides the legal question in the first instance based on the input of interested agencies, his legal judgment is inevitably skewed a great deal by wanting to uphold his policy. OLC (and any executive branch lawyer) faces this danger to some degree, but the danger is less pronounced when the initial decision is made in a relatively independent legal office in DOJ as compared to the Oval Office.In my view, however, more is at stake than getting a "sound legal decision" -- it's about making good presidential decisions of any kind. Presidents sometimes may feel that it is, on balance, worth the risks to oppose legal precedent, but they certainly should know that's what they're up to when they do it. Similarly, presidents may at times believe that the risks of following expert opinion on military affairs, or economic policy, or any other area are greater than the risks of bucking that opinion. Presidents see things (or at least should see things) from many angles, and they may be aware of all sorts of very good reasons to override experts who may, for all their wisdom, have a narrower view. But that makes it all the more important for the president to be fully informed of exactly what qualified experts say. And, in this case, that means following procedures that will produce a thoroughly vetted legal opinion.
The point, here, isn't that Obama is engaging in tyranny or lawlessness; it's that presidents who try to run their presidents this way wind up, more often than not, harming themselves. That sort of presidency just doesn't work well. The office is tough enough to handle well even when the president collects all the information available; without it, he's risking all sorts of dangers.