Observers have been wildly ruminating on the various implications of the U.S.-Iran cease-fire agreement, the so-called Islamabad Memorandum of Understanding. Alongside the MOU’s political, military, and economic import, a key legal question looms: Is it a binding international agreement—in other words, a treaty governed by international law—or a political text signaling intent without legally binding the parties? The Trump administration is likely to insist that the MOU is not a treaty, if only to avoid domestic obstacles such as congressional approval. The text itself contains elements of both, creating risks on the agreement’s consequences and overall validity. In short, this was a hastily and poorly drafted effort.
Treaties have existed for millennia, whereas informal political agreements have a more recent origin. Of the latter, one of the first known examples is the 1907-08 Gentlemen’s Agreement between the United States and the Japanese Empire to restrict migration. The concept is not hard to understand: As individuals, we make all sorts of promises—some legally binding, some not. Breaching a lease can have legal consequences, such as eviction, whereas not showing up at a dinner party invites nothing more than interpersonal tensions. In international relations, states have seen real value in making agreements without formal legal status because they can be done more quickly and skirt various obstacles, of which legislative approval is only one. Treaties, for example, often require notice before they can be terminated. Witness the first Trump administration’s frustration about the three-year window required under the Paris Agreement before any state could withdraw—and then only on one year’s notice. The Trump administration reluctantly adhered to these conditions.
Observers have been wildly ruminating on the various implications of the U.S.-Iran cease-fire agreement, the so-called Islamabad Memorandum of Understanding. Alongside the MOU’s political, military, and economic import, a key legal question looms: Is it a binding international agreement—in other words, a treaty governed by international law—or a political text signaling intent without legally binding the parties? The Trump administration is likely to insist that the MOU is not a treaty, if only to avoid domestic obstacles such as congressional approval. The text itself contains elements of both, creating risks on the agreement’s consequences and overall validity. In short, this was a hastily and poorly drafted effort.
Treaties have existed for millennia, whereas informal political agreements have a more recent origin. Of the latter, one of the first known examples is the 1907-08 Gentlemen’s Agreement between the United States and the Japanese Empire to restrict migration. The concept is not hard to understand: As individuals, we make all sorts of promises—some legally binding, some not. Breaching a lease can have legal consequences, such as eviction, whereas not showing up at a dinner party invites nothing more than interpersonal tensions. In international relations, states have seen real value in making agreements without formal legal status because they can be done more quickly and skirt various obstacles, of which legislative approval is only one. Treaties, for example, often require notice before they can be terminated. Witness the first Trump administration’s frustration about the three-year window required under the Paris Agreement before any state could withdraw—and then only on one year’s notice. The Trump administration reluctantly adhered to these conditions.
As easy as it may be to distinguish binding and nonbinding agreements conceptually, actual practice has proved tricky. The legal status of the Joint Comprehensive Plan of Action (JCPOA)—the Obama-era Iran nuclear deal—was also contested. U.S. officials were adamant that it was not legally binding without a U.N. Security Council resolution. But Iranian officials insisted that international law governed the text and denounced the first Trump administration’s subsequent disavowal of it. Since then, policymakers have been wrestling with how to draw these lines, including in the U.N. International Law Commission, the Council of Europe, and the Organization of American States, where I helped develop some guidelines.
Why should we care if the MOU is a treaty or not? One issue is what happens in case of noncompliance, where only treaties trigger consequences under international law. Sometimes those consequences are spelled out in the treaty itself—such as binding dispute settlement or terms for suspending the breaching party. More generally, international law authorizes the injured state to take “countermeasures”—otherwise unlawful behavior that is automatically excused for the injured state because of the prior treaty breach. So, if the MOU is a treaty, its breach could actually justify future, otherwise wrongful conduct in ways that a nonbinding political commitment would not.
Second, if it’s a treaty under international law, the United States will need domestic legal authority to conclude the MOU. Some treaties go to the Senate for formal ratification under Article 2 of the U.S. Constitution; others get prior or subsequent congressional approval as “congressional executive agreements,” while a third category involves those binding treaties that can be done under presidential executive powers only. The JCPOA avoided all three categories, given the Obama administration’s insistence that it was nonbinding. Congress pushed back by enacting the Iran Nuclear Agreement Review Act, which requires that any agreements involving the United States and Iran on nonproliferation be sent to Congress and makes it illegal for the White House to remove sanctions before a 30-day review period ends.
There is already speculation that Trump is ignoring this law as he takes steps to remove sanctions. But if the MOU is a treaty, then there is an additional legal basis for Congress to insist on reviewing the text. As with Trump’s tariff deals, the MOU might require congressional authorization. Or is the MOU akin to bilateral defense agreements, which are traditionally regarded as treaties that a president can make autonomously? Consider Paragraph 6 of the MOU: “The United States of America undertakes with regional partners to develop a definitive, mutually agreed plan with at least USD 300 billion for the reconstruction and economic development of the Islamic Republic of Iran.” The language is imprecise, but Congress might read it as implying a financial commitment that runs afoul of the Constitution’s Appropriations Clause if legislators are not involved.
On the other hand, the White House might emphasize that the MOU is only an “agreement to agree,” given that it anticipates that “implementation … will be finalized as part of a final deal within 60 days.” The reference to doing this with “regional partners” offers additional wiggle room. Ultimately, though, it will be up to Congress to make its own judgment on whether these are legal commitments and, if so, whether to offer the requisite approvals. (The phrase “final deal”—not exactly traditional diplomatic language—of course raises a whole other round of similar questions.)
Finally, there is an even more fundamental reason to care whether this MOU is a treaty or not: Treaties are governed by international law, specifically the Vienna Convention on the Law of Treaties. This convention went into force in 1980; today, 119 states are bound by its terms. Although the United States is not a party, it has accepted most of its provisions as customary international law. And that past acceptance may come back to bite: Article 52 of the convention states: “A treaty is void if its conclusion has been procured by the threat or use of force in violation of the principles of international law embodied in the Charter of the United Nations.” The charter, in turn, prohibits the threat and use of force, except in cases of self-defense or with U.N. Security Council authorization. Coerced treaties, such as the infamous 1938 Munich Agreement, are thus unlawful.
For most of the international law community, there’s little question that the U.S. attack on Iran violated the use of force prohibition. Iran subsequently flexed its own power in closing the Strait of Hormuz, so that, for all practical purposes, may have been Iran coercing Trump to sign the MOU. The law, however, will likely focus on the original illegality of the U.S. bombings. If the MOU is a treaty, Iran may thus have legal grounds to ignore it, giving it further maneuvering room in the coming 60 days of negotiations. How to fix this issue? In debates over a Russia-Ukraine settlement, some have argued that the U.N. Security Council has the power to legalize an otherwise clearly unlawful Russian occupation. If so, there’s value to Paragraph 14 of the MOU promising Security Council approval—although it’s unclear how Washington and Tehran can promise that in a bilateral agreement.
So, is the MOU a treaty or not? Under international law, two criteria identify a treaty. First, is there an agreement with clear commitments? This distinguishes treaties from the other things that states sign, such as G-7 summit declarations. The MOU fulfills this criterion. Consider Paragraph 4, which states that immediately on signing, the United States will begin removing its naval blockade. In Paragraph 5, Iran pledges to make arrangements—“using its best efforts”—for commercial vessels to safely pass through Hormuz without charge for 60 days. Stipulations such as these clearly make this an international agreement.
Second, is the agreement governed by international law? This turns on an examination of the text, surrounding circumstances, and subsequent practice. As things stand, that analysis produces a decidedly murky picture, although there’s still time for Washington and Tehran to jointly clarify the MOU’s status.
On the nonbinding side of the ledger, there are textual markers suggesting that the Trump administration did not envision creating a treaty. The title “MOU” is likely to be relevant, especially given Trump’s prior views. During his first term, Trump got into a public dispute with U.S. Trade Representative Robert Lighthizer over whether MOUs are binding or not. Trump argued that an MOU could never be legally binding, presumably based on his experience in commercial real estate, where such agreements explicitly signal nonbinding intent. In international practice, however, the “MOU” moniker can be used for both binding and nonbinding agreements. The text’s use of “paragraphs” instead of “articles” also reflects the sort of wordsmithing that international lawyers use to delineate a nonbinding political commitment. The absence of any mention of a dispute settlement mechanism and the lack of final clauses specifying entry into force further favor treating this as a nonbinding agreement.
Other textual cues cut the other way. The MOU references the United States and Iran having “jointly agreed.” The word “agree” and “agreement” are usually reserved for binding texts. The same can be said of the preamble’s reference to “good faith,” another typical element of legally binding language.
Then there is the “will” problem. Parties looking to signal a treaty often employ “shall,” and when looking to avoid a treaty commitment, they use “should.” Hence, the Paris Agreement was almost scuppered over a last-minute change of a “should” to “shall.” The MOU regularly employs neither of these but largely uses “will” to delimit the signatories’ future expected behavior. There is no international agreement over what “will” means: The United States has long suggested that the word can be binding or nonbinding, depending on the context in which it is used. Britain, on the other hand, consistently defines it as a nonbinding expression of intent. This difference is why, in 1994, the United States insisted on renegotiating intelligence-sharing agreements with Britain and Canada that were replete with the verb “will”; once Washington learned that its allies viewed the agreements as nonbinding, it insisted on revisions to make their treaty status clear.
A similar dispute will loom over the MOU’s use of “undertake.” This term was highlighted by a Supreme Court majority in Medellín v. Texas as being the sort of conditional commitment that cannot demand immediate judicial enforcement. But international practice has long treated “undertake” as akin to “shall” in conveying a legally binding intent. If the White House is following Supreme Court precedent, then perhaps these references to “undertake” further instantiate the idea of the MOU as a nonbinding instrument. But it is not clear that others, including Iran, will agree.
Ultimately, a review of the MOU suggests just how hastily and haphazardly it was devised. After all, the opening text suggests commitments that will extend not just to Iran and the United States but also to “their allies.” International law makes this undisputably invalid: States are only bound by agreements to which they explicitly consent; third-party obligations in the MOU will thus require the approval of whichever allies are expected to adhere.
Given that subsequent practice can help define an agreement’s binding or nonbinding status, there is still time for the two parties to alleviate the confusion by jointly signaling their views on what kind of agreement they just signed. As important as the nuclear proliferation and humanitarian stakes of the deal are (and they are huge), the question of the MOU’s legal status will have far-reaching consequences under international and domestic law. These consequences may themselves impact whether and how the MOU is implemented—to say nothing of the “final deal” it contemplates.
