Barack Obama ignored the formal opinions of senior professional legal staff in the Department of Justice on the Libya campaign:

President Obama rejected the views of top lawyers at the Pentagon and the Justice Department when he decided that he had the legal authority to continue American military participation in the air war in Libya without Congressional authorization, according to officials familiar with internal administration deliberations.

Jeh C. Johnson, the Pentagon general counsel, and Caroline D. Krass, the acting head of the Justice Department’s Office of Legal Counsel, had told the White House that they believed that the United States military’s activities in the NATO-led air war amounted to “hostilities.” Under the War Powers Resolution, that would have required Mr. Obama to terminate or scale back the mission after May 20.

But Mr. Obama decided instead to adopt the legal analysis of several other senior members of his legal team — including the White House counsel, Robert Bauer, and the State Department legal adviser, Harold H. Koh — who argued that the United States military’s activities fell short of “hostilities.” Under that view, Mr. Obama needed no permission from Congress to continue the mission unchanged.

Presidents have the legal authority to override the legal conclusions of the Office of Legal Counsel and to act in a manner that is contrary to its advice, but it is extraordinarily rare for that to happen. Under normal circumstances, the office’s interpretation of the law is legally binding on the executive branch.

If there is a defining legacy of the Obama administration, it may be in the formalization of the Nixonian principle that if the President does it, regardless of the settled law, it’s legal.

Perhaps it’s time to dispense with our unique form of government, and move to a parliamentary one, because if there are no constraints on the executive beyond elections, then the political system must be able to force elections at times like this.