President Obama is facing a swell of bipartisan criticism for continuing military engagement in Libya without congressional approval. Even supporters of the Libya intervention have complained that the administration is flouting the law.

So, is it?  

Well, the president is certainly sidestepping the controversial law known as the War Powers Act, but in doing so he’s following a well-worn path.  

The Vietnam-era law requires the president to seek approval from Congress after 60 days of military engagement. The law was passed in 1973 after the United States fought the Korean and Vietnam wars without actual declarations of war. But it’s always been controversial. (President Nixon actually vetoed the law, but Congress overrode him.)

According to a 2004 Congressional Research Service report, “every President since the enactment of the War Powers Resolution has taken the position that it is an unconstitutional infringement on the President’s authority as Commander-in-Chief.”

President Obama, in defending the legitimacy of the Libyan operation, hasn’t actually made that argument. On Wednesday, he submitted a report to Congress arguing that his administration isn’t in violation of the act at all, despite the fact that the 60-day deadline for congressional approval of Libya operations came and went in May.  

White House spokesman Jay Carney has argued that the United States’ “constrained and limited operations” in Libya “do not amount to hostilities” because the United States doesn’t have or intend to place soldiers on the ground and has not sustained the casualties typical of such hostilities.

The United States in April pulled its cruise missiles and attack planes out of combat in the NATO-led Libyan mission, though it still has them on standby. It’s currently providing support such as aerial refueling, surveillance and reconnaissance, according to the AP.

Speaker of the House John Boehner has said the White House’s stance “doesn’t pass the straight-face test.”

President Obama is far from alone in finding creative ways around the War Powers Act. As the New York Times has noted, the Clinton administration continued the bombing campaign in Kosovo past the 60-day deadline, arguing that Congress had implicitly approved the mission when it approved funding for it. (The Act specifically says that funding doesn’t constitute authorization, the Times notes. And Obama wouldn’t be able to use that reasoning anyway—the administration is using existing funds for the Libya mission.)

Clinton’s successor, President George W. Bush, did request—and receive—a resolution of support from Congress for the Iraq war, but Bush also made clear that his compliance with the War Powers Act didn’t mean he agreed with the act’s constitutionality. Here’s what he said [PDF], as quoted in a Congressional Research Service report:

As I made clear to congressional leaders at the outset, my request for congressional support did not, and my signing this resolution does not, constitute any change in the long-standing positions of the executive branch on either the President’s constitutional authority to use the Armed Forces to defend vital U.S. interests or the constitutionality of the War Powers Resolution.

While presidents have long inveighed against the act, lawmakers have just as frequently invoked it, often as a political weapon.  

This week, a bipartisan group of 10 House members—a combination of Republicans and antiwar Democrats—sued the Obama administration this week over the War Powers Act. But the move may be little more than symbolic. As NPR notes, lawmakers have never successfully used the War Powers Act to end any military mission, and in 2000, the Supreme Court refused to touch the issue when lawmakers complained about Kosovo.

It’s also worth keeping in mind that many of Obama’s critics seem a bit conflicted about the legitimacy of the act. As Politico has reported, Boehner—who sent a confrontational letter to the president this week—actually voted to repeal the law in 1995. In 1999, he called it “constitutionally suspect.” Boehner’s spokesman said the speaker has an obligation to honor existing law “regardless of his personal views.”

But Boehner’s also been unclear about whether Obama is even violating the act. Two weeks ago, Boehner said that “technically,” he wasn’t: “Legally, they’ve met their requirements [under] the War Powers Act,” he said of the administration.

(On Libya, Boehner has said that the United States “has a moral obligation to stand with those who seek freedom from oppression and self-government for their people” and called Libyan dictator Muammar Qaddafi’s actions “unacceptable and outrageous.”)

As the House ups the ante on the War Powers Act, Sens. John Kerry and John McCain are advancing a bipartisan resolution to support the U.S. role in Libya. (McCain, a Republican, has criticized Obama administration’s reasoning as “a confusing breach of common sense.”)

As we’ve noted, the Obama administration has sought to downplay its role in the Libya conflict since it began in March—though there’s been some mission creep: The Obama administration originally said that the goal of the intervention was not regime change in Libya, but it has since suggested that its measure for success will be Qaddafi’s departure.