Columbia Law School, Class of 2015
In 2011, governments around the world committed to deliver a new, universal, and binding greenhouse gas (GHG) reduction agreement for the period beyond 2020 by 2015. This agreement is to be adopted this December at the twenty-first Conference of the Parties to the United Nations Framework Convention on Climate Change (UNFCCC) in Paris, France. The credibility and overall success of the so-called ‘Paris Agreement’ is tied to whether the United States, as one of the planet’s foremost emitters of GHGs, enters into it. President Obama has clearly signaled his intention to do so. But, given the politics of climate change in the United States, it is almost certain that the Senate will not ratify the agreement. This will inevitably lead some to question the agreement’s constitutional basis and legal effect.
The traditional view is that under Article II of the United States Constitution two-thirds of the Senate must provide their backing to allow any international agreement to bind the United States into a course of action. But conventional alternatives to Article II ratification do exist. As the Supreme Court noted in United States v. Belmont, there are “many such [international] compacts, of which a protocol, a modus vivendi, a postal convention, and agreements … are illustrations,” that “do not require the participation of the Senate.” Such internationally binding agreements are not uncommon; in fact, they are five times more prevalent than agreements entered into through the Article II process.
As former Sabin Center fellow Hannah Chang has explained, legal scholars have divided these conventional alternatives into three categories: sole-executive agreements, congressional-executive agreements, and treaty-executive agreements.
Sole-executive agreements are those agreements where the President makes international law based on his or her independent constitutional authority. Sole-executive agreements are uncommon compared to the other two, and focus primarily on military and other foreign affairs matters where the constitutional strength of the President is at its strongest. Treaty-executive agreements are those agreements that the President enters into pursuant to an express or implied authorization in an existing Article II treaty. Congressional-executive agreements are agreements that are entered into by the President pursuant to legislation specifically authorizing such an agreement. This authorization can be ex ante, as with the International Dolphin Conservation Act of 1992, or it can be ex post, where Congress enacts legislation authorizing an agreement after its negotiation.
The anticipated Paris Agreement does not fit neatly into any of these categories. The scope of domestic regulation necessary to reduce GHG emissions makes the Agreement an unlikely candidate for a sole-executive agreement. Similarly, although some commentators have pointed to both the UNFCCC and the Convention on International Civil Aviation as potential bases for a treaty-executive agreement, those treaties would arguably only reach measurement and reporting measures (UNFCCC) or controlling emissions from airplanes (CICA). Finally, there is no existing or foreseeable congressional legislation that expressly establishes the grounds for a congressional-executive agreement.
Nonetheless, a court might be able to find that a Paris Agreement committing the United States to reduce GHG emissions is within the President’s constitutional authority. Indeed, Justice Jackson in Youngstown Sheet & Tube Co. v. Sawyer famously described a sliding scale of congressional authorization for presidential actions that reflects a broad spectrum of forms of congressional approval and the functional inter-dependency of the branches. When the President acts with the express authorization of Congress, his power is at its absolute maximum, and should be given the “widest latitude of judicial interpretation” and “supported by the strongest of presumptions.” Where Congress has denied the President the power to act, his power is at its minimum. As Harold Koh, former Legal Adviser to the State Department, has noted, the attempts of academics to place international agreements into particular “boxes,” such as “sole-executive agreement” or “congressional-executive agreement,” narrows Justice Jackson’s spectrum into unnecessarily discrete categories. In short, there is room for agreements that fit between the “boxes.” The Minamata Convention provides an example, and a potential precedent, for the Paris Agreement.
The Minamata Convention on Mercury (“Minamata Convention”), among other things, bans primary mercury mining, requires permits for trade in pure mercury, and regulates specific mercury products, processes, and releases to air, land, and water.  It was accepted by the United States when Dr. Kerri-Ann Jones, Assistant Secretary of State for Oceans and International Environmental and Scientific Affairs, serving as a representative of the President, deposited an Instrument of Acceptance at the United Nations Headquarters in November 2013.
The Minamata Convention is plainly not an Article II treaty. Nor is it a congressional-executive or treaty-executive agreement either. The Minamata Convention might be considered a sole-executive agreement, but it is not focused on the “central” Presidential domains of foreign policy and national security.
In a press release, the State Department justified its approach to entering into the Minamata Convention with the following:
The Minamata Convention represents a global step forward to reduce exposure to mercury, a toxic chemical with significant health effects on the brain and nervous system. The United States has already taken significant steps to reduce the amount of mercury we generate and release to the environment, and can implement Convention obligations under existing legislative and regulatory authority. The Minamata Convention complements domestic measures by addressing the transnational nature of the problem.
This justification can be split roughly into three prongs: 1) the United States had already taken “significant steps” to fulfill the obligations of the treaty; 2) the obligations can be implemented under “existing legislative and regulatory authority”; and 3) the treaty complements domestic measures by tackling the “transnational nature” of the problem. The first prong provides a practical justification – it will not take much effort, a fact that buttresses the argument of existing executive authority. The second prong claims an implied authority drawn from an existing legislative mandate under the Clean Air Act. The rationale here is that the President can infer congressional authorization to enter into an international agreement where congressionally delegated authority allows for actions that will fulfill its obligations. The third prong alludes to the President’s power to govern foreign affairs.
Taken together, then, the Minamata Convention offers a mix of characteristics that appears to fall along Justice Jackson’s spectrum between the levels of legislative support given to sole-executive and congressional-executive agreements: no express legislative authorization, but some measure of presidential authority implied by an existing delegation and tied to the executive’s foreign policy powers.
If the State Department sought to justify unilaterally entering into the Paris Agreement in the same way, its defensibility may depend on the final wording of the Agreement. If, as anticipated, the obligations take the form of nationally determined GHG emission reduction contributions – which would bind countries only to those commitments determined by their own domestic governments – then the President’s authority would be implied by the Clean Air Act, as affirmed by the Supreme Court’s decision in Massachusetts v. EPA and implemented by EPA’s subsequent regulation of GHG emissions. This would be analogous to the justification used for the Minamata Convention. However, if the text of the agreement would commit countries to internationally determined contributions the justification becomes trickier. The Minamata Convention did not impose additional requirements on the United States beyond those it already intended to meet.
However, even if the Paris Agreement were constitutional, it is possible that Congress could return the President’s power to its minimum through a strong-enough showing of disapproval. Such an action would “transform” the agreement into a pure sole-executive agreement, making it potentially more susceptible to legal challenge.
The standard for a sufficient showing of congressional disapproval is high. In Dames & Moore v. Regan, President Carter agreed to terminate legal proceedings against Iran and to nullify attachments obtained in such proceedings. The Supreme Court noted that, because Congress “ha[d] not enacted legislation, or even passed a resolution, indicating its displeasure,” it had not “resisted the exercise of Presidential authority.” Some have thus concluded that, as a consequence, the Court has implicitly created a presumption of legislative acquiescence in executive agreements, absent specific congressional disapproval.
Arguably Congress has already expressed a limited disapproval of some GHG emissions reduction agreements in the Byrd-Hagel Resolution of 1997. That resolution expressed the sense of the Senate that the United States should not accept any agreement that would mandate new commitments to limit or reduce GHG emissions by developed countries unless the agreement also mandated new specific scheduled commitments to limit or reduce emissions by developing countries within the same compliance period. Thus, one might expect that any agreement that commits the United States to emissions reductions without committing developing nations could fail.
What’s more, the passing of legislation that explicitly disapproves of the terms of the Agreement could amount to a sufficient showing that Congress is “resisting the exercise of Presidential authority.”
In sum, the question of whether the President could constitutionally enter into the Paris Agreement without Senate approval in the same way as the Minamata Convention can be answered in the affirmative if certain conditions are met. The text of the Agreement must bind the United States to domestically-determined GHG emission reductions; the Agreement must not utilize a developed/developing country dichotomy; and Congress must not enact legislation specifically removing its support. If these conditions are satisfied there may indeed be a sound legal justification for acting without the Senate in signing the United States up for a new global climate agreement in Paris.
 United States v. Belmont, 301 U.S. 324, 330 (1937) (“But an international compact, as this was, is not always a treaty which requires the participation of the Senate.”).
 See U.S. Senate, Powers & Procedures: Treaties, available at https://www.senate.gov/artandhistory/history/common/briefing/Treaties.htm (last visited May 8, 2014) (“The United States is currently a party to nearly nine hundred treaties and more than five thousand executive agreements.”).
 Hannah Chang, International Executive Agreements on Climate Change, 35 Columbia J. Envtl. L. 337, 341 (2010), available at https://blogs.law.columbia.edu/climatechange/files/2015/02/INTERNATIONAL-EXECUTIVE-AGREEMENTS-ON-CLIMATE-CHANGE.pdf.
 Id. at 362.
 Youngstown Sheet & Tube Co. v. Sawyer, 343 U.S. 579, 635 (1952) (“While the Constitution diffuses power the better to secure liberty, it also contemplates that practice will integrate the dispersed powers into a workable government. It enjoins upon its branches separateness but interdependence, autonomy but reciprocity. Presidential powers are not fixed but fluctuate, depending upon their disjunction or conjunction with those of Congress. We may well begin by a somewhat over-simplified grouping of practical situations in which a President may doubt, or others may challenge, his powers, and by distinguishing roughly the legal consequences of this factor of relativity.”).
 Id. at 637.
 Harold Hongju Koh, Remarks: Twenty-First-Century International Lawmaking, 101 Geo. L.J. 725, 732 (2013).
 National Interest Analysis: Minamata Convention on Mercury, Government of New Zealand, available at https://www.mfe.govt.nz/laws/meas/national-interest-analysis-minamata-convention-mercury.pdf.
 Global Treaty on Mercury Pollution Gets Boost from United States, Minamata Convention on Mercury Website (2013). https://www.mercuryconvention.org/News/GlobalTreatyonMercuryPollutionGetsBoostfrom/tabid/3524/Default.aspx.
 Harlow v. Fitzgerald, 457 U.S. 800, 812 n.19 (1982).
 Media Note, U.S. Department of State, United States Joins Minamata Convention on Mercury (Nov. 6, 2013), available at https://www.state.gov/r/pa/prs/ps/2013/11/217295.htm.
 Dames & Moore v. Regan, 453 U.S. 654, 688 (1981).
 Id. at 655.
 Lee P. Marks & John C. Grabow, The President’s Foreign Economic Powers After Dames & Moore v. Regan: Legislation by Acquiescence, 68 Cornell L. Rev. 68, 102-03 (1982).
 S. 98, 105th Cong. (1997).