On August 17, 1787—exactly one month before the close of the Constitutional Convention at Philadelphia—the Framers of what eventually became the US Constitution were laboring over the wording of a critical government power: the power over war, peace, and foreign affairs. In this famous debate, memorialized in James Madison’s famous Notes on the Convention, we find important lessons for today.

On that crucial August day, the Framers refined the division of the war power between Congress and the president. Congress—and not the president—was given the power to declare war. But the president—and not Congress—was left with the power to defend against attacks, to conduct war as Commander in Chief, and to make peace (by treaty or otherwise) as an aspect of his general power over foreign affairs.

Constitutional Distinctions

The precise issue on the table that morning was the provision of the draft Constitution giving Congress the power “to make war.” Madison’s notes report, first, an objection from “Mr. Pinkney” to “vesting this power in the Legislature” as its proceedings were “too slow.” Other delegates added their criticism of the ability of the legislative branch to make quick determinations.

Then Madison and Massachusetts delegate Elbridge Gerry—who, many years later, during the War of 1812, would become Madison’s vice president—proposed a subtle but important change in the language “to insert ‘declare,’ striking out ‘make’ war, leaving to the Executive the power to repel sudden attacks.” After much further discussion, the motion was adopted. Rufus King of Massachusetts contributed the observation that “make” war might be understood to include the power to “conduct” war, which was an executive function, which persuaded Connecticut to join in support of the change.

The Framers also considered, but rejected, a motion to add the words “and peace” to Congress’s power to declare war, probably because matters of truce, treaty negotiation, and foreign affairs generally were considered properly executive. (The Treaty Clause of Article II provides that the president may make treaties only with the advice and consent of the Senate, by a favorable vote of two-thirds.) It was only the power to initiate a condition of war that the delegates thought crucial to vest in the legislative branch.

Though the Framers’ Philadelphia debates are cryptic and contradictory at times, several points seem clear. First, the provision was understood to vest in Congress, and not in the president, the decision whether the nation should go to war. Second, the change from “make” to “declare” was considered an improvement because it would leave with the president the traditionally understood executive power to defend the nation against attacks, thereby providing for those situations where Congress would be too slow in acting to protect the security of the nation. Third, the change from “make” to “declare” would avoid confusion about who had the power to conduct—to execute—war. That power, all seemed to agree, was the president’s alone, both as a matter of the executive power and as reinforced by the clause empowering the president as “Commander in Chief” of the nation’s armed forces. Fourth, and finally, the power to make or declare peace—the power of diplomacy and the conduct of foreign affairs generally—appears specifically to have been withheld from Congress and left with the president.

Declaring and Conducting War in Practice

How well have recent presidents and Congresses adhered to the Constitution’s division of the powers of war and peace? Not very: Many modern presidents have asserted the power to take the nation into a state of war without prior congressional authorization.

Notorious examples include President George H.W. Bush, who famously asserted that he didn’t need permission from “some old goat in Congress” before launching the Gulf War of 1991. In the end, however, Congress did authorize the Gulf War, making it completely constitutional.

So too lawyers for the next President Bush—George W. Bush—asserted unilateral presidential war-making authority but nonetheless actually obtained full authorization from Congress. The sweeping “Authorization for Use of Military Force” of September 18, 2001, is the constitutional equivalent of a declaration of war, and a stunningly sweeping one: It authorizes “all necessary and appropriate force” against persons, nations, or organizations connected or affiliated, directly or indirectly, with the September 11 attacks—essentially al Qaeda and its allies, franchises, affiliates, and harboring nation-states. That authorization remains in force today. Bush also obtained a separate, overlapping authorization for the use of military force in Iraq.

President Barack Obama, perhaps surprisingly, has been the most flagrant in flouting the Constitution’s allocation of war powers, engaging in offensive force against Libya in 2011 without any constitutionally sufficient authorization. His lawyers defended the action on the ridiculous theory that it is not a “war” if the president doesn’t think it’s a “war,” that military action served United States interests, and that past presidents have done things such as this. (The last point is true, but irrelevant: President Truman waged the Korean War without congressional authorization. That doesn’t change the meaning of the Constitution; it simply means that the Korean War, whatever its moral merit, was unconstitutional. The same can be said for President Clinton’s months-long sustained air war in Kosovo in 1999: perhaps morally justified, but still constitutionally deficient.)

In 2013, President Obama also asserted that he did not need authorization to attack Syria’s regime for its use of chemical weapons, but then backpedaled and asked Congress for the authority he said he didn’t need, before finally abandoning the whole matter into the trusty hands of Vladimir Putin. Most recently, President Obama this past winter proposed a new authorization to use force against ISIS in Syria and Iraq. But his bewildering proposal both ignored the fact that the September 18, 2001, authorization already covered this al Qaeda spinoff and actually constituted a proposed de-authorization of military authority by limiting its length to three years. For good reason, Obama’s disingenuous de-authorization went nowhere. (He’s waging war against ISIS on the basis of the prior authorization.)

Congress has been no better, frequently ignoring the Constitution’s assignment of the war-conducting power to the president as Commander in Chief and trying to micro-manage war from the legislative sidecar. While the Constitution admits of certain legislative powers in conjunction with carrying out war, Congress cannot constitutionally employ these powers in such a fashion as to hamper the president’s sole power to decide when, how, and where to use force in an authorized military action and, further, to determine policies of engagement, capture, detention, and military punishment with respect to an enemy force or power. Congress’s power “to declare War” is an on-off switch; it is not a “dimmer switch” with which to control the Commander in Chief.

Finally, there is the power to make—or preserve—peace. Ever since President George Washington declared American neutrality in 1793 (in the then-latest war between France and Britain), it has been well established that Congress’s power to authorize war is not a power to prevent the president from declaring neutrality or to interfere in any other respect with the executive’s power to formulate and conduct the foreign affairs policies for the nation. Congress probably cannot even make the president fight a declared war against his will. And it certainly cannot prevent the president from declaring an armistice or truce. True, the president can only make a “treaty”—a formal legal arrangement that has the force of US law under the Constitution’s supremacy clause—with the Senate’s two-thirds consent. But the president may interpret, apply, and even suspend treaties, and can even enter into (nonbinding) “executive agreements” with foreign nations as part of the general executive power over foreign affairs. The “executive agreement” power is simply an application of the ordinary foreign affairs authority of the president, albeit an application with dramatically important implications.

For better or for worse, President Obama’s deal with Iran falls into this last category. It is not a treaty, so it is not binding law under the US Constitution—and it does not constrain a future administration’s decisions, other than as a matter of domestic and international politics. Congress need not approve it, and has no true constitutional power to defeat it; Congress’s only power is with respect to legislative imposition or removal of economic and trade sanctions against Iran, as part of its power to regulate international commerce. (The legislation earlier adopted to give Congress a “vote” on the Iran deal is really a vote over sanctions, and it is structured so as now to give Obama the upper hand: he ultimately gets his way unless Congress can now pass a disapproval resolution over his veto.)

In all of this, one can hear the echoes of August 17, 1787. Under the Constitution—at least as originally designed—Congress has the power to declare war, but not the power to prohibit peace or interfere with the conduct of foreign affairs. The president has the power to defend the nation by repelling attacks, and the power to conduct a war authorized by Congress as he sees fit, but no legitimate power to initiate offensive military hostilities against an enemy force or power on his own authority. Certainly not all of America’s practice for the past 228 years has conformed to the Framers’ design. But that does not mean that the meaning of the Constitution with respect to the powers of war and peace has changed. It means that the Constitution has, in several instances, been violated.