In what has become a painfully familiar scenario, President Donald Trump announced on May 29, 2020 his decision to withdraw the United States from a long-established treaty arrangement: this time the United States’ participation in the World Health Organization (WHO). Set aside for a moment whether Trump’s decision was motivated by a desire to deflect attention from his own incompetent response to an infectious virus that has now resulted in 100,000 American deaths (compared to fewer than 300 deaths in the South Korea, which also reported its first COVID-19 case on the same day in January as the first American case was reported). Nor need we explore as a policy matter whether the U.S. would be better off mending, rather than ending, its relationship with an organization it helped found and build. Nor finally, need we review the myriad medical reasons—underscored recently by the Infectious Diseases Society of America and the former head of the Centers for Disease Control and Prevention— why it is foolish and counterproductive for a nation at the epicenter of a global pandemic to withdraw from the organization dedicated to fighting global pandemics.

For now there are two immediate legal questions: first, has Trump actually withdrawn the United States from the WHO? The answer is no. Second, if Congress or public health advocates see things differently, are they powerless to prevent WHO withdrawal from happening? Again, the answer is no. There is much they can and should still do.

Let’s start by recognizing that, as a matter of law, Trump has not yet taken any meaningful legal action. Instead, he has issued a letter, a tweet, and a statement to the WHO Health Assembly. In a threatening May 18 letter sent to the WHO’s Director General, Trump declared his intent to suspend U.S. contributions to the organization and stated that “if the World Health Organization does not commit to major substantive improvements within the next 30 days [by June 18], I will make my temporary freeze of United States funding to the World Health Organization permanent and reconsider our membership in the organization.”

In reality, it’s not so simple.

In 1948, the United States became one of the state members of the WHO Constitution (now numbering 193 nations)—a document whose terms it helped draft in New York. Upon joining, the United States “accept[ed] this [WHO] Constitution in accordance with the provisions of [the WHO Constitution] and in accordance with [U.S.] constitutional processes,” under Article 4 of the international instrument.

What about withdrawing? The WHO Constitution lacks an explicit withdrawal provision. So to address this gap, the U.S. Congress passed a Joint Resolution (Public Law 643, 80th Congress, June 14, 1948) authorizing the President to accept U.S. membership in the WHO and specifying that the United States would not withdraw from the WHO except upon satisfaction of two conditions:

In adopting this joint resolution the Congress does so with the understanding that, in the absence of any provision in the World Health Organization Constitution for withdrawal from the organization, [1] the United States reserves its right to withdraw from the organization on a one-year notice: [2] Provided, however, that the financial obligations of the United States to the organization shall be met in full for the organization’s current fiscal year.

President Harry Truman’s statement of U.S. acceptance of the WHO Constitution expressly acknowledged that he was “acting pursuant to the authority granted by the joint resolution … and subject to the provisions of that joint resolution.” (62 Stat. 2792 (1948).) The World Health Assembly then unanimously “recognized the validity of the ratification by the United States” on July 2, 1948.

Because the same Joint Resolution authorized an annual appropriation to the State Department for the payment of the U.S. share of the expenses of the organization, the Joint Resolution imposed its dual conditions on the president by exercising both Congress’ constitutional power to approve treaties and its power of the purse. As Justice Jackson famously observed in the Steel Seizure case, Youngstown Sheet & Tube Co. v. Sawyer, “[p]residential powers”—in this case, to withdraw from binding international agreements of the United States—“are not fixed but fluctuate, depending upon their disjunction or conjunction with those of Congress.” By seeking to act contrary to both of Congress’ stated conditions, President Trump’s actions fall into Category Three of Justice Jackson’s famous tripartite Steel Seizure framework, where the President’s constitutional power stands at “its lowest ebb.” Indeed, it is fair to say Trump has no legal authority to withdraw the United States from the WHO without satisfying the two conditions.

At this moment, it does not appear that Trump has yet sent the WHO Director General any formal notice of withdrawal. But under these two congressional conditions, first, the United States remains obliged to meet its financial obligations to the WHO in full for the current fiscal year. Second, the United States may not legally withdraw from the WHO Constitution at the earliest one year until at least from the date that Trump sends a formal withdrawal notice – in other words, sometime in mid-2021, at which point, of course, Donald Trump may no longer be president.

So what does his “withdrawal” really mean?

Not much. First and most obviously, if Joe Biden is elected president, he need only renounce Trump’s claimed withdrawal before it is scheduled to take legal effect, which would be four months or more after a President Biden would take office.

Second, should Trump be reelected, the United States would still be legally obliged to pay the balance of its 2020 assessed contribution: roughly $60 million, to fulfill one of the two congressional conditions. (For 2020, the assessed contribution is about $120 million, of which the United States has already paid half.) That is due not only to the Joint Resolution, but also to the existence of congressionally approved funds for the WHO. As Speaker Nancy Pelosi recently argued, failure to pay the WHO would violate the same legal rule that the nonpartisan Governmental Accountability Office (GAO) determined the White House violated in delaying congressionally authorized funding for Ukraine, a matter at issue during the Trump impeachment.

Third, even if Trump were to wait until one year’s notice had elapsed, nothing prevents Congress from enacting a subsequent joint resolution that strengthens the terms of U.S. withdrawal from the WHO, for example, by extending the time for withdrawal to two years, or subjecting withdrawal explicitly to congressional approval by joint resolution. I have elsewhere argued at length that the president does not have unilateral constitutional power to withdraw the United States from any and all international agreements. Instead, I suggested:

In the modern era, an agreement-specific mirror principle—requiring parity of constitutional authority for entry and exit from an international agreement—represents a far better functional reading of the Constitution than a claimed general unilateral right of the president to terminate any and all international agreements.

In the case of the WHO, the United States entered the organization through an executive agreement subsequently approved by a joint resolution of Congress. The mirror principle would dictate that it could constitutionally leave only with the enactment and approval of a subsequent, mirroring joint resolution authorizing withdrawal. Should Congress adopt bipartisan bills—paralleling its “No NATO Withdrawal” bills—preemptively disapproving final U.S. withdrawal from the WHO in 2021, then as a constitutional matter, to effectuate his withdrawal plan, Trump would need not only to veto that joint resolution of disapproval, but also to secure from a potentially Democratic Congress a new joint resolution approving such withdrawal in 2021.  As in the Gramm-Rudman budget case, Bowsher v. Synar, Congress could include within a joint resolution a congressional provision conferring standing on any individual Member to challenge a presidential withdrawal effectuated without members having any opportunity to vote on a joint resolution approving WHO withdrawal.

Fourth and finally, private litigants need not wait for Congress to act. If sometime in mid-2021, a reelected Trump attempted to complete a WHO withdrawal, litigation would almost certainly ensue. Plaintiffs with standing could include members of Congress with statutory standing, private entities and states and localities adversely affected by U.S. disengagement, and perhaps afflicted individuals who had been denied by the withdrawal the benefits of WHO-endorsed testing. Under Zivotofsky v. Clinton, the Supreme Court would have little basis, for reasons I have pointed out elsewhere, for dismissing the matter as a political question. At a moment when their lawsuit was clearly ripe, the plaintiffs could—even before the final date of withdrawal— seek a declaratory judgment that Trump’s attempt to unilaterally terminate U.S. participation in the WHO would be unconstitutional, unless made by and with the full consultation or approval of both Houses of Congress. If so, Trump’s letter and tweets would be a vain attempt at a legal act whose completion a court has found unconstitutional, absent express congressional approval. More simply put, they would have all the legal significance of a letter to my mother.

Surely, the Justice Department would defend Trump’s prerogatives by overreading the Supreme Court’s forty-year-old summary disposition in Goldwater v. Carter, which found nonreviewable one attempted unilateral bilateral treaty termination, President Carter’s unilateral termination of a mutual defense treaty with Taiwan upon the formal U.S. recognition of the People’s Republic of China. But even in Goldwater, the Justices splintered, never reasoning on the merits regarding who must constitutionally decide before the United States has conclusively withdrawn from an international agreement. Indeed, four crucial votes found a political question that would be invalid today, after Zivotofsky. And in Goldwater, none of the nine Justices embraced a rule favoring a general unilateral power of presidential treaty termination, particularly when Congress expressly objects. To the contrary, four Justices observed “that different termination procedures may be appropriate for different treaties,” which should logically lead to a context-dependent rule such as the mirror principle discussed above.

Fairly read, Goldwater, far from being controlling, is beside the point. Goldwater says nothing at all about five features that distinguish its facts from the current WHO withdrawal scenario: (1) a withdrawal from an agreement that is multilateral, not bilateral; (2) a withdrawal arguably not implemented in accordance with the original congressional terms for withdrawal; (3) a withdrawal carried out within the scope of Congress’s plenary authority over the power of the purse, not the president’s exclusive power to recognize foreign states; (4) a withdrawal potentially attempted in the face of explicit congressional opposition; and (5) a withdrawal not from an obsolete bilateral treaty derecognizing a foreign government, but from a major international organization addressing a major global health emergency.

Some commentators have sought to justify unilateral presidential withdrawal under a functional “quick divorce” argument, where (as in the Taiwan treaty case) foreign affairs exigencies may require the United States to exit, with haste, from entangling alliances that have been overtaken by events.  This functional theory deems the president alone as best situated to decide whether and when a quick divorce is necessary. But in the modern era, this reasoning applies to relatively few international agreements, and certainly not to long-term membership in a global organization like WHO, in which membership is not just transactional, but relational. U.S. membership in specialized international organizations does not authorize sequential, one-off transactions so much as it creates for all parties organic, evolving relationships that generate a deeply interconnected set of rights, duties, expectations, and reliance that become internalized into U.S. law and practice. As the global COVID-19 crisis has graphically taught, the disruptive act of withdrawal from the WHO does not only engage the transient interests of one man, Donald Trump. Instead, WHO withdrawal would impact the broader long-term interests of Congress, our allies, the WHO and other international organizations, and states and localities. Perhaps most important, millions of embattled American citizens and residents rely on the WHO’s pronouncements, declarations, and coordination to identify and mitigate not just the coronavirus pandemic, but other pandemics and public health threats that we can yet only imagine.

Ironically, even as President Trump invokes his myopically transactional approach to international affairs, condemning all manner of international agreements as “bad deals,” his Solicitor General recently made the opposite, relational argument in Jam v. International Finance Corp., correctly noting that the “United States’ participation in international organizations is a critical component of the Nation’s foreign relations [that] reflects an understanding that robust multilateral engagement is a crucial tool in advancing national interests.”

Nor should it matter, as some have argued, that recent historical practice has included some uncontested unilateral presidential withdrawals from other international agreements. The Justice Department would surely cite past unilateral presidential withdrawals from other international organizations, such as UNESCO, to which Congress did not object. But this historical practice has limited relevance. In INS v. Chadha, the Supreme Court famously invalidated the legislative veto, even though 295 legislative vetoes had been inserted into nearly 200 statutes in the previous half-century. Despite this history, and policy clams made for the “functional usefulness” of the legislative veto, Chadha held the legislative veto not just justiciable but unconstitutional, noting that “policy arguments supporting even ‘political inventions’ are subject to the demands of the Constitution.” The Court should accordingly set aside examples of uncontested unilateral presidential withdrawals, which do not raise the constitutional question here: whose decision should prevail when the branches disagree?

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In sum, Trump’s empty threat to withdraw from the WHO is far from complete. His action has been loudly launched, but like so much of his noisy foreign policy, it is far from executed. In Goldwater, Judge George MacKinnon presciently warned, “In future years, a voracious President and Department of State may easily use this grant of absolute power [of unilateral termination] to the President to develop other excuses to feed upon congressional prerogatives that a Congress lacking in vigilance allows to lapse into desuetude.” It would be grievous error, in the waning days of his first and perhaps only term, for an impeached, mercurial president (or his lawyers) to assume that our Constitution confides in Trump alone the power to disengage the United States from the WHO, or other crucial international organizations that make up the post-World War II legal order.

U.S. President Donald Trump, trailed by Treasury Secretary Steven Mnuchin (R) and Secretary of State Mike Pompeo (2nd R), walks to the Rose Garden to make a statement on May 29, 2020 (Win McNamee/Getty Images)