Last night, nine days after we began bombing Libya, President Obama went on television to explain what we’re up to and what the plan is. It’s always nice to be kept in the loop.

But the real outrage here isn’t that Obama — for once — has been reluctant to make a speech. It’s that our Nobel Peace Prize-winning, former constitutional law professor president has launched yet another war in the Middle East without any constitutional authority for doing so.

Equally offensive is the emerging legal pretext for the war, in which UN authorization supposedly eliminates the need for a congressional vote. “Why not go to Congress?” ABC’s Jake Tapper asked Secretary of State Hillary Clinton on Sunday. “We would welcome congressional support,” Clinton replied, but this is an “internationally authorized intervention.”

Why go to Capitol Hill when you’ve already got permission from Turtle Bay?

In a speech last weekend, State Department legal adviser Harold Hongju Koh fleshed out the argument: there’s “ample international legal authority” for the Libyan adventure, he said, citing the UN Charter and the Security Council Resolution authorizing a no-fly zone. “In sum, the United States’ military actions in Libya are lawful.”

Well, no, they’re not. After all, the Constitution requires the president to “consult with Congress and receive its affirmative authorization — not merely present it with faits accomplis — before engaging in war.”

That’s according to one Harold Hongju Koh, in a November 1990 legal brief challenging the first president Bush’s contention that he could fight the Gulf War on his own authority (Bush later sought and received a use-of-force resolution from Congress).

In a past life, you see, Koh was a vocal critic of Republican presidents’ unauthorized wars. In his berth at the State Department, though, he’s grown in office, becoming a full-fledged apologist for Tomahawk humanitarianism. (It profits a man nothing to give his soul for the whole world … but for Foggy Bottom?)

But Security Council approval was no substitute for congressional authorization in the Gulf War, and it’s no substitute here. Bully for President Obama that he got sign-offs from rotating members of the UNSC like Colombia, Gabon, and Lebanon — and the approval of permanent members like France and Britain. He’s got the support of the New Republic editorial board too. None of that constitutes actual legal authority, in the form of a vote by the American people’s representatives in Congress.

As congressional scholar Louis Fisher points out in his book Presidential War Power, nothing in the text or history of the UN Charter and the UN Participation Act purports to cede Congress’s constitutional powers over war and peace to the so-called “international community.” “Congress did not — it could not — do that,” Fisher writes. President Woodrow Wilson’s League of Nations had gone down to defeat on precisely this point, and in acceding to the UN, Congress sought to protect its constitutional prerogatives.

Obama’s argument that UN “authorization” allows him to bypass Congress isn’t unprecedented. Harry Truman made it in Korea, as did Bill Clinton in Haiti. But, as before, this argument “violates the U.S. Constitution,” misinterprets UN authority and “represents an effort through the treaty process to strip from the House of Representatives its constitutional role in matters of war.”

“How long,” Fisher asks, “do we drift in these currents before discovering the waters are hazardous for constitutional government?”

Covering the outrage brewing in some quarters on the Hill, Politico quotes an irate Democratic congressman: “They consulted the Arab League. They consulted the United Nations. They did not consult the United States Congress.”

That’s what we’ve come to. Will Congress put up with it?