Can Obama strike Syria alone?

Under the United States Constitution, does the president have the power to use military force in Syria on his own? Or does he need congressional permission?

Last week, 140 members of the U.S. House of Representatives signed a letter insisting that military action “without prior congressional authorization would violate the separation of powers that is clearly delineated in the Constitution.” But even while seeking permission to use force in Syria, President Barack Obama objected, “I have the authority to carry out this military action without specific congressional authorization.”

The disagreement is older than the Republic. Because of the nature of emerging threats, it is likely to become even more heated in coming years. To understand the opposing positions, we need to step back a bit. (Before we do, two disclosures: I am serving as a member of the president’s Review Group on Intelligence and Communications Technology; my wife, Samantha Power, is the U.S. ambassador to the United Nations and is thus involved in Syria policy.)

The Constitution makes the president the commander in chief of the armed forces. But it gives Congress, not the president, the power “to declare war.” That power emerged from an illuminating debate at the Constitutional Convention in 1787.

An early draft would have given Congress the power “to make war.” Charles Pinckney objected that legislative “proceedings were too slow,” and that the “Senate would be the best depositary, being more acquainted with foreign affairs, and most capable of proper resolutions.” Pierce Butler strongly disagreed, responding that the power should be vested “in the president, who will have all the requisite qualities, and will not make war but when the nation will support it.”

At that point James Madison and Elbridge Gerry moved to strike out the word “make” and replace it with “declare,” an apparent compromise “leaving to the executive the power to repel sudden attacks.” Roger Sherman approved of this language on the ground that the president should “be able to repel and not to commence war.” A strong majority agreed to the “declare war” language.

During and soon after the founding era, many people endorsed the view that while the president could respond to sudden attacks, he could not make war on his own. In the Pennsylvania Ratifying Convention, for example, James Wilson said that under the Constitution, the decision whether to go to war “will not be in the power of a single man, or a single body of men.” Thomas Jefferson wrote that under the Constitution, “one effectual check to the dog of war” was “transferring the power of letting him loose from the executive to the legislative body.”

This conclusion seems to support the view that Obama needs legislative authorization to act in Syria. But there is nonetheless a defense of presidential authority, which is that the commander in chief doesn’t require Congress’s support to engage in military actions that fall short of “war.” In 1941, Attorney General Robert Jackson observed, “the president’s authority has long been recognized as extending to the dispatch of armed forces outside of the United States,” not only to protect American lives but also “on missions of goodwill or rescue.”

In the last three decades, both Republican and Democratic presidents have built on this rationale to justify a variety of military actions lacking congressional authorization, for example, in Libya (1986), Panama (1989), Somalia (1992), Bosnia (1995), Haiti (twice, 1994 and 2004) and Serbia (1999).

Under this rationale, we need to distinguish between a limited military mission and an actual “war.” In making that distinction, the Department of Justice has pointed to the relevance of two factors: the magnitude of the action (including its scope, nature and duration) and its underlying justification.

A protracted engagement would have to count as a war. The same isn’t true for an action that extends for days or weeks. But even if it is brief, a large-scale action that is intended as a kind of invasion, meant to assert American authority over another nation, should almost certainly be deemed a war.

By contrast, a short-term action that is designed to protect narrow national security interests might not be so counted. Consider a targeted effort to help stabilize a region of keen importance to the U.S. Similarly, it might be argued that the international norm against use of chemical weapons, reflected in the Chemical Weapons Convention, promotes the security interests of the U.S., and that the use of force, meant to deter erosion of that norm, would promote those interests.

In this light, President Obama’s claim of authority to act unilaterally is reasonable, certainly if any military action would be short-lived. But both academic observers and members of Congress have raised constitutional doubts - which argues in favor of his decision to seek legislative authorization whether or not it is strictly required.

*The author, the Robert Walmsley University professor at Harvard Law School, is a Bloomberg View columnist. He is the former administrator of the White House Office of Information and Regulatory Affairs, the co-author of “Nudge” and author of “Simpler: The Future of Government.”