U.S. airstrikes against Libya have reignited the perennial debate over whether the president can launch military operations without first securing congressional approval. The answer is found in the Constitution’s text and history, and it must be the same regardless of the president’s political party. Those Republicans accusing President Obama of exceeding his legitimate authority should consider whether they would make the same claims if a Republican were president, as many Democrats previously have done.

The Constitution’s Framers deliberately divided war powers between the president and Congress. As commander in chief, the president has the authority to determine when and how U.S. forces are used. Congress, on the other hand, has the power to raise, support and make rules governing the armed forces, and to determine how much is to be spent in war or peace. Individual officers can be appointed only if the Senate approves, and only Congress can declare war. The debate over the president’s use of force without congressional authorization focuses on this provision.

When the Constitution was adopted, the power to “declare war” was not equivalent to permitting the use of military force.

Nations could, and did, use force without declaring war on their opponents. As a matter of international law, a declaration of war had much more to do with the technical legal regime governing hostilities — dissolving treaties between the belligerent powers and permitting the lawful seizure of public or private enemy property, for example — than with the right to use force in the first place.

The Framers understood this. The British monarch was not only commander in chief but also could declare war. The Framers divided this authority, reserving the latter power to Congress as the national legislature. During the Constitutional Convention, the power to “declare war” was substituted for the power to “make war” in defining congressional authority specifically to clarify that the president could use military force without first seeking Congress’s permission. According to James Madison, the particular concern was that the president should be able to “repel sudden attack.”

Champions of congressional warmaking powers traditionally point to this comment as limiting the president’s independent war powers to defending American soil, but even Madison’s remark was not so narrowly drawn, and the Constitution’s language is not so limited. It gives the president wide latitude to use military force, subject always to the other limits on his authority inherent in congressional control over the budget, size and existence of the national military.

Consistent with this understanding, presidents often have launched military operations without first seeking congressional approval.

Their actions have been more or less controversial depending on the nature, extent and purpose of those operations. Certainly at some point, depending on the extent, purpose and likely duration of hostilities — regime change in Iraq, say — a president must seek congressional approval, either in the form of a declaration of war or less formal use-of-force authorization.

As a practical matter, he may also want that approval to ensure sufficient political support and resources to continue a particular operation, even if not constitutionally required. Congressional authorization also is often critical in defending his actions. It was, for example, Congress’s specific authorization for the use of force against those responsible for the Sept. 11, 2001, attacks that led the Supreme Court to uphold the detention of captured al-Qaeda and Taliban operatives, including American citizens.

Justifying the current operations against Libya in this framework is not difficult. Moammar Gaddafi has been an open and persistent enemy of the United States for nearly 40 years. He pioneered state sponsorship of terror attacks against U.S. nationals and others, bombing a Berlin disco in 1986 and a passenger aircraft over Lockerbie, Scotland, in 1988. After the Berlin attack, President Ronald Reagan ordered (also without specific congressional authority) U.S. airstrikes against Libya. If ever there were a ripe candidate for “regime change,” it is Gaddafi.

The Obama administration, however, has not suggested anything so ambitious. The stated goal is to enforce a U.N. Security Council-approved “no-fly zone” as a means of limiting Gaddafi’s ability to attack his citizens. The United States has a right and an obligation as a U.N. member assisting in the implementation of a binding Security Council resolution to take this action — and it is not of a character that would constitutionally require Congress’s approval. If the president later concludes that Gaddafi should be removed by American arms — no small matter given the nation’s other military commitments in Afghanistan and Iraq — then congressional approval can and should be sought.

The authors served in the Justice Department under presidents Ronald Reagan and George H.W. Bush.