FRIDAY MARKS the 60th day in which the United States has been involved in the U.N.-sanctioned military operation in Libya. The two-month anniversary confronts the Obama administration with a difficult question: Will it obey the law — specifically the War Powers Resolution?

That act, passed in 1973 in response to the Vietnam War, allows the president to commit troops to hostilities without congressional authorization for 60 days. Once he has reached that milestone, the president must get congressional approval or suspend operations. The act allows one 30-day extension but only to ensure the safe and orderly withdrawal of military forces.

We supported President Obama’s decision to join allies from NATO to prevent the potential massacre of thousands at the hands of Libyan strongman Moammar Gaddafi; that mission clearly has not yet been accomplished and would probably be set back should the United States pull out. We have also long harbored doubts about the wisdom of the War Powers Resolution, threatening as it does to permit Congress to infringe on the president’s constitutional authority to command and direct military operations. This tension is palpable, but ignoring the War Powers Resolution — or offering disingenuous arguments about why it does not apply — is not the answer.

An assertion that congressional approval is unnecessary because NATO — and not the United States — is waging the Libyan conflict is not persuasive and ignores the fact that NATO weapons and personnel are supplied and directed by member countries, including the United States. Arguments that the United States is no longer involved in hostilities also fall short. As recently as late April, the United States conducted military strikes using drones. “The president has said where we have unique capabilities, he is willing to use those,” Defense Secretary Robert Gates said at the time — and rightly so. Even if the administration is now only supplying intelligence and other support, that is part of war fighting — and the uncertainties of conflict may again require more kinetic (to use a recently favored euphemism) military involvement.

The administration seems not even to have tried to secure Congress’s buy-in before the Friday deadline. Rather than dodge compliance, the president should seek congressional authorization next week, once both chambers are back in session. As the Supreme Court has noted, the president’s powers are at their highest when he acts in concert with Congress. In this case, Mr. Obama’s flexibility in taking appropriate action in Libya would be enhanced by securing Congress’s endorsement.

Should Congress refuse, the president has another, although less palatable, option. If he believes that continued involvement is vital to U.S. security and to protecting Libyan innocents, he should inform Congress and the public about his intention of going forward with the campaign, openly challenge the constitutionality of the War Powers Resolution and work toward its repeal or amendment. We sympathize with his dilemma, but ignoring the law of the land is not an acceptable way out.