Conservatives have much to criticize in President Obama’s deal with Iran on its nuclear program. The agreement allows Iran to operate sophisticated nuclear equipment, keep its suspected weapons labs open, and maintain stockpiles of nuclear material with ample opportunity to manipulate international inspectors. Washington and its allies must lift crippling sanctions and release $150 billion in frozen assets now, while hoping that Iran will refrain from developing an atomic bomb for the next decade.

Some conservatives may argue that Obama is violating the law, too. The Treaty Clause declares that the president “shall have Power, by and with the Advice and Consent of the Senate to make Treaties, provided two thirds of the Senators present concur.” Instead of following this process, set out in Article II, Section 2, of the Constitution, President Obama plans to codify the deal as an executive agreement without the Senate’s supermajority approval. The Iran deal appears to run counter to decades of practice by the elected branches, which have used the Treaty Clause to make almost every significant arms-control agreement, such as the Test Ban Treaty, Anti-Ballistic Missile Treaty, the INF, and the START and New START pacts.

But critics of the Iran deal should save their strength when it comes to the Constitution. Last spring, Republicans in Congress created a process to review the agreement by majority vote. If Congress disapproves the deal, President Obama can still veto the resolution. In other words, two-thirds of the House and Senate will have to agree to stop the Iran deal — a bizarre inversion of the Treaty Clause.

Congressional Republicans may have scored a political victory by putting every Senate Democrat on the record on the Iran deal, but they have also inadvertently bolstered the deal’s legality. In foreign affairs, as the Supreme Court has observed, the president acts at the height of his constitutional powers when backed up by Congress. In Youngstown Sheet & Tube v. Sawyer, which blocked President Truman’s seizure of the nation’s steel mills during the Korean War, Justice Robert Jackson famously observed: “When the President acts pursuant to an express or implied authorization of Congress, his authority is at its maximum, for it includes all that he possesses in his own right plus all that Congress can delegate.” While only a concurrence (and one I tend to disagree with as a misreading of the separation of powers), Jackson’s approach has found its way into the justices’ majority opinions in recent foreign-affairs cases.

In providing a legal basis for the Iran deal, congressional Republicans have only themselves to blame. Nevertheless, conservatives are weighing legal challenges in court. This would be a waste of valuable resources.

First, a lawsuit would ask courts to stretch their jurisdiction beyond their proper scope. It is unlikely that such a challenge would arise from a plaintiff with standing — the requirement that the person who brings suit has suffered a discrete injury directly traceable to the government action. Simply claiming that the United States or the Constitution has suffered harm is not enough to walk into federal court. Conservatives have struggled for a generation to rein in judges who use flimsy lawsuits as an excuse to engage in policymaking and social engineering. To manufacture standing to bring a political dispute into court would descend to the level of liberal judicial activists who continue to use the judiciary to invent new rights and interfere with the proper balance of powers between the branches of government. The courts will probably turn away such a challenge, and they should.

Second, a lawsuit would foist an unduly narrow reading of the Treaty Clause on the nation’s foreign affairs. Not all international agreements must take the form of Article II treaties. Congress enacts some pacts — such as NAFTA, WTO, and the coming Trans-Pacific Partnership — as regular statutes through simple majority votes in Congress. Presidents have reached some agreements unilaterally, such as FDR’s recognition of the Soviet Union and Jimmy Carter’s deal to free the Iranian hostages.

The line between international agreements that must take the treaty form and those that need not remains obscure (for my own effort at explaining the difference, see my article “Laws as Treaties?: The Constitutionality of Congressional-Executive Agreements” in Michigan Law Review in 2000). I think that Congress can use laws in some areas, such as economic sanctions and trade, to make agreements because they fall within Congress’s exclusive authority under the Commerce Clause. Agreements that pose serious limits on the United States’ sovereignty and that make long-lasting military and security commitments, such as peace treaties and alliances, must take the form of treaties. Difficulty in finding the line between the two does not mean that the line is not there; nor does it mean that critics are right that the federal government can make international agreements only through the Treaty Clause.

In fact, the Iranian deal skirts the boundaries of a treaty in a way too clever by half — so clever, in fact, that it contains the seeds of its own undoing. Obama-administration officials argue that the agreement need not take the treaty form because it is not legally binding under international law. Instead, the deal represents a series of political commitments. There are neither agencies to enforce the agreement nor courts to resolve disputes. The agreement makes no commitment to future actions by the United States; nor does it limit our sovereignty, as would a promise to refrain from the use of military force. Its only significant promise is that Obama will grant a waiver under existing laws lifting economic sanctions under Iran, which as a presidential promise requires no new action by Congress.

Under this approach, though, the president who occupies the Oval Office in January 2017 can undo the deal with little delay. Presidents have long terminated treaties on their own, but the practice has generated controversy over the years and has never met with the definitive approval of the Supreme Court (though the justices refused to block President Carter’s termination of the Taiwan mutual-defense treaty, they could not agree on the reason). An unsparing textualist could argue that the Constitution should require the same method to unmake a treaty as to make it, while defenders of the presidency would respond that treaty termination, like firing inferior officers, remains with the executive branch. But whatever one’s stance on treaty termination, no one doubts that today’s president can undo the actions of earlier presidents. Just as a president can repeal earlier executive orders on his own, so too can a president terminate international agreement without anyone else’s say-so.

Obama’s defenders, and even some critics, might respond that the U.N.’s blessing of the Iran deal could restrain the next president’s freedom of maneuver. Last week, the administration won unanimous approval for the agreement in the U.N. Security Council, which under international law had to lift economic sanctions and reverse its prohibitions on Iran’s nuclear program (a humiliating request for American diplomats to make). Liberals no doubt will argue that the United States must obey the Security Council resolution under the U.N. Charter, a treaty that assumes the status of supreme federal law.

Security Council resolutions, however, do not bind the president as a matter of domestic law. In a series of cases where the International Court of Justice attempted to block the death penalty in the U.S., the Supreme Court made clear that the branches of the federal government owe no constitutional obeisance to international bodies. The next president can cross the Security Council, just as earlier presidents have ignored U.N. efforts to interfere with U.S. national-security objectives, such as the covert war against Nicaragua or battling with the Iranians in the Persian Gulf.

Third, a lawsuit demands that conservatives turn their back on their vigorous defense of presidential power in national security and foreign affairs. The Constitution contains startling silences, not least of which is the grant of control over foreign policy to either the president or Congress. The Framers explicitly split treaty-making between the president and Senate, gave the president the role of commander-in-chief and Congress the power to declare war and raise armies, and required that the Senate approve the president’s appointment of ambassadors. Political scientist Edwin Corwin famously observed that this arrangement created “an invitation to struggle” over directing foreign policy.

Into this textual vacuum, the president’s institutional advantages and historical practice have come to the fore. As Alexander Hamilton first argued in defense of President George Washington’s proclamation of neutrality in the French Revolution, Article I of the Constitution vested in Congress carefully limited powers, such as the power to regulate interstate commerce, declare war, and raise and support armies. Article II, however, vested in the president “the executive power,” without enumerating its content. Any power by nature executive, such as representing the nation in its foreign affairs, must accrue to the president, except for powers that the Constitution explicitly transferred elsewhere. “The general doctrine then of our Constitution is that the Executive Power of the Nation is vested in the President,” Hamilton concluded, “subject only to the exceptions and qualifications which are expressed in that instrument.”

Hamilton argued that the conduct of foreign relations was fundamentally executive in nature under British constitutional practice and the theories of Locke, Blackstone, and Montesquieu. Therefore, Article II’s vesting of executive power in the president gave Washington the right to decide not to intervene in what would become the Napoleonic Wars. It should be noted that Hamilton was not a fair-weather friend of executive power. During the ratification contest, he had argued as Publius in Federalist No. 72 that “the actual conduct of foreign negotiations,” “the arrangement of the army and navy,” and “the directions of the operations of war” should fall “peculiarly within the province of the executive department.”

Attacking Hamilton, Madison set out the case for congressional control over foreign affairs that endures to this day. He dismissed Locke and Montesquieu’s classification of foreign affairs as executive in nature, because they were “evidently warped by a regard to the particular government of England.” Making treaties and declaring war were legislative powers because they had the force of law; therefore, the president could not exercise them. “The natural province of the executive magistrate is to execute laws, as that of the legislature is to make laws,” Madison wrote. “All his acts therefore, properly executive, must presuppose the existence of the laws to be executed.” To allow the president a share of the legislative power “is an absurdity — in practice a tyranny.” Madison’s deeper argument was that placing the power to conduct war and to begin war in the same hands risked tyranny. “Those who are to conduct a war cannot in the nature of things be proper or safe judges whether a war ought to be commenced, continued, or concluded.” According to Madison, “war is in fact the true nurse of executive aggrandizement.”

Madison’s arguments, however, failed. Washington proclaimed neutrality. Even Thomas Jefferson, who had urged Madison to attack Hamilton and who established the Democratic party to challenge Washington, would exercise broad executive authority once he moved into the Oval Office. Ever since the Hamilton–Madison debate, presidents have exercised the initiative in foreign affairs, punctuated by periods — such as the 1930s Neutrality Acts — in which Congress has used its power over international commerce and military funding to push the nation in a different direction. Conservatives have long defended the executive’s prerogatives in foreign affairs based on Hamilton’s arguments, from Nixon’s expansion of bombing in Vietnam, Reagan’s invasion of Grenada, George H. W. Bush’s Persian Gulf War, and President George W. Bush’s war on terror and invasion of Iraq (on which I worked as an official in the Justice Department).

Today, conservatives disagree with President Obama’s use of these constitutional reservoirs of power to reach for the mirage of a rapproachment with Iran. But those same powers have served presidents from Lincoln, who invoked broad executive power to fight the Civil War and free the slaves, to FDR, who brought the nation into the war against the Axis powers, to Truman and Reagan, who, respectively, oversaw the Cold War at its beginning and toward its end. The next president will need those powers again when he or she quickly turns policy toward Iran in the opposite direction.

In the next weeks, conservatives will have ample opportunity to persuade the American people against the Iran deal on its merits. Presidential candidates will explain the steps they will take to undo the damage that Obama has inflicted on our national security. But they will make a serious mistake if they seek the short-term political end of defeating the Iran deal by crippling the Presidency’s long-term powers to defend the nation.

Crossposted at National Review Online