The U.S. can't quit the Paris climate agreement, because it never actually joined

President Trump (Andrew Harnik/Associated Press)

President Trump is expected to announce today that the United States will not be party to the Paris agreement on climate change. What he should say is that the United States never properly joined the accord: It is a treaty that requires the advice and consent of the Senate. Instead, President Barack Obama choose to "adopt" it with an executive order last September.

Two features cut heavily against it being treated as the kind of arrangement that can be entered into by a president on his own authority. First, it has a four-year waiting period for withdrawal, quite unlike traditional executive agreements. Second, it is a large multilateral deal, and the other parties apparently believe it requires domestic ratification. Whatever that means for U.S. constitutional purposes, it does suggest that other countries should hardly protest if Trump merely follows their example to seek domestic ratification.

Some general principles are worth reviewing. In international law, the term "treaty" is one of the many terms for a binding international agreement. Not all agreements that are "treaties" in the international law sense - i.e., that create a binding international obligation - are "Treaties" in the constitutional sense. It is well accepted that there is a class of international agreements that the president can commit the United States to on his own authority, without invoking the treaty process. However, the scope of the "sole executive agreement" (SOE) category is a matter of great dispute.

Some scholars have gone so far as to argue that the Paris agreement represents an exotic and previously unidentified species of international deal that does not have to be treated as a treaty. But even in this view, if Obama was within his rights to treat it as a non-treaty, Trump would be entirely within his executive rights to interpret it differently - as a treaty requiring Senate consent, which has not even been sought yet.

While there are no clear rules about the treaty/executive agreement, the Paris accord has some features, not yet analyzed in this context, that do not follow the pattern of past SOEs. So simply pointing out that there are such things as SOEs does not mean this is one of them, given that it departs from the SOE model in significant ways.

1. The four-year withdrawal provision.
The climate accord has a four-year delayed exit period, which would raise serious constitutional problems if it were a SOE instead of a treaty. A country party to the deal can withdraw only four years after giving notice of its intent to do so. This is quite extraordinary. Most treaties do not provide for any waiting period for withdrawal; it is a fairly significant substantive term. But many treaties do have such terms - almost invariably shorter than four years. Indeed, six months or a year are the most common waiting period, and I know of no treaty to which the United States is party with one as long as four years.

But for an executive agreement, such restrictions are truly remarkable and go far beyond the kind of "thin" agreement allowed under sole executive authority. Indeed, I am not sure there is a single SOE that has any substantial withdrawal restriction at all. The justification of SOEs is that they are an inherent part of a president's foreign affairs powers, because the conduct of foreign affairs requires frequent formal arrangements between countries. But the president can also unmake them as needed.

A extended withdrawal period in a SOE would allow one president to unilaterally pre-commit his successor and limit the latter's powers. Moreover, the four-year period does not appear accidental, but rather, designed to limit Trump's ability to exit: If he does not do so now, his potential successor will have the ability to cancel the withdrawal before it takes effect.

To be sure, a president can always quit a SOE as a matter of domestic law, but if the SOE is valid ab initio, this would breach international commitments, making it harder for the subsequent president to use his executive authority. Indeed, this is precisely the argument made against Trump now.

Such a deep commitment cannot be made without the involvement of the Senate. This quite unusual feature of Obama's agreement strongly suggests it cannot be treated as a SOE, and thus has no force until the Senate ratifies it.

2. The United States is an outlier in not seeking domestic ratification for the accord.
Some argue that even if Trump's non-acceptance of obligations under the agreement would be consistent with the Constitution, it would be a breach of an international obligation and weaken foreign trust in U.S. commitments. Yet foreign countries are in no place to complain if the United States insists on treating the agreement as a treaty requiring submission to the legislature - because that is exactly how they have treated it themselves.

Indeed, the real U.S. exceptionalism would be not in Trump's action, but in Obama's - in not seeking ratification.

Countries seem invariably to have accepted the agreement as a treaty that requires going through their internal treaty-ratification processes, typically submission to the legislature. Countries from the United Kingdom to China to Jamaica have ratified it through their legislatures. So has Brazil, Japan, the Philippines and Australia. In the latter, the question of whether it was a binding international accord requiring submission to Parliament received some discussion, and a parliamentary analysis concluded it was a "major treaty" that needed to be submitted.

I know of no country that has taken the U.S. approach. All countries seem to understand that ratification requires using the domestic procedure for ratifying treaties.

The universal interpretation of the agreement as a treaty cuts against Obama's insistence that it is not one. (It should also be noted that SOEs for multilateral agreements are themselves almost unheard of, and certainly not for global ones.) A treaty is an international agreement, and in a multilateral treaty, the views of other signatories are at least probative of the question of whether it creates binding obligations upon ratification.

To be sure, the question of what kind of agreements must be submitted to the Senate is not governed by foreign countries' rules about treaty ratification. The U.S. definition of "treaty" for constitutional purposes is considerably narrower than the definition of treaty in international law. The definition in various other countries' constitutions may also be broader and narrower. So it is not the other countries' decision to seek legislative ratification that is relevant, but rather, the view that it creates binding international commitments.

That is not to say that the status of agreement in international law and practice is irrelevant to its domestic constitutional status. Indeed, from the earliest cases, courts have looked to international law for the purpose of distinguishing treaties from other agreements. The writings of Vattel, the international law author most familiar to the framers, have played a large role in these discussions.

Indeed, the Supreme Court has suggested that the international legal trappings of an agreement are relevant to the constitutional treaty/sole executive agreement distinction. See Holmes v. Jennison, 39 U.S. 540, 571 (1840) ("For when we speak of 'a treaty' we mean an instrument written and executed with the formalities customary among nations.") (Taney, C.J.)

In short, Trump is not quitting the Paris accord. The United States was never in it in the first place.

I should note that these observations are culled from an ongoing academic look at the provisions of the agreement. Some of the issues - such as the relevance of other parties' ratification practice - are quite interesting and complex. I offer them here now to shed at least some light on the events of the day.