Saved by Silence: Climate Change, Treaty Lacunae, and the U.S.-Mexico-Canada Agreement

24 Pages Posted: 25 Mar 2022

See all articles by Tracy Hester

Tracy Hester

University of Houston Law Center

Date Written: November 30, 2021


Like a gap-tooth smile, the United States-Mexico-Canada Agreement (USMCA) pointedly lacks any explicit provision on—or even mention of—climate change. The absence of such a prominent concern in one of the world’s largest free-trade agreements might seem odd, but this omission did not arise from neglect or simple oversight by the negotiating teams. Given the Trump Administration’s high-profile opposition to significant regulatory action on climate change, Prime Minister Justin Trudeau’s commitment to a vigorous climate policy by Canada, and the shifting flows of Mexico’s climate policies due to presidential election outcomes, the lack of language on climate in the USMCA was not a surprise. The more salient question is whether the Parties’ conscious and deliberate choice to exclude discussion of anthropogenic climate change hobbles the USMCA’s power to govern trade issues affected by climate change policies or effects.

This Article explores the final text and genesis of the USMCA and its implementation by the Parties to trace their careful excision of climate change. The negotiators’ painstaking climate change navigation, upon close examination, does not suggest an intent to bar application of the USMCA to climate change concerns. The agreement’s deliberate lacunae instead seems to mark a careful preservation of the issue for future consideration under other, more general, provisions of the agreement. This approach accords with long-standing international legal precedents on the interpretation of treaties and the interpretive value of deliberate omissions from treaty language. If this view of the USMCA holds true, it offers important opportunities for the Parties to raise climate change concerns and coordinated actions that affect trade and adequate enforcement of environmental standards by the Parties.

Keywords: environmental law, climate change law, USMCA, trade law, treaty interpretation, international law

JEL Classification: K32, K33

Suggested Citation

Hester, Tracy, Saved by Silence: Climate Change, Treaty Lacunae, and the U.S.-Mexico-Canada Agreement (November 30, 2021). --- Vermont L. Rev. --- (2021), Available at SSRN: or

Tracy Hester (Contact Author)

University of Houston Law Center ( email )

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713-743-1152 (Phone)


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