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An American (State) in Paris – Can States Commit to the Paris Agreement?

Monday, November 12, 2018

The United States’ decision to withdraw from the Paris Agreement was a shock to environmentalists and the international community. In response, individual U.S. states took it upon themselves to pledge their commitment to the Paris Agreement without federal support. However, some scholars observed that state involvement in the Paris Agreement may be unconstitutional, a potential violation of the Supremacy Clause, Treaty Clause, and Compact Clause.

In An American (State) in Paris: The Constitutionality of U.S. States’ Commitments to the Paris Agreement, the winner of ELI’s 2017-2018 Henry L. Diamond Constitutional Environmental Law Writing Competition, Kristen McCarthy argues that states’ involvement does not violate the U.S. Constitution. Moreover, she writes, it also may set a precedent for state involvement in future environmental international agreements.

After the Trump Administration’s announcement, state response to continue the Paris objectives was almost immediate. Hawaii was the first state to pledge to follow Paris, followed by 15 other states and Puerto Rico. The governors of California, New York, and Washington formed a U.S. Climate Alliance to collectively uphold the United States’ commitment of reducing greenhouse gas emissions by 26-28% below 2005 levels by 2025 through investments in clean energy and transportation. States, cities, mayors, and organizations stepped up to announce their support.


In response to scholarly critiques of state action, McCarthy’s analysis of the Supremacy Clause, Treaty Clause, and Compact Clause make the case that states are authorized to join the agreement without federal support. First, she argues that there is no express statutory preemption for state action regarding governing greenhouse gas emissions, and there is also no implied preemption because there is no federal regulatory regime currently in place to monitor and reduce emissions. Next, she asserts that voluntary commitments to the Paris Agreement do not violate the Treaty Clause because “individual states are not considered real Parties to the Agreement,” and that the agreement is not considered a treaty. Finally, she argues that states’ commitment to Paris “do not interfere with the supremacy of the United States or form any legally enforceable compact,” and that the agreement is non-binding.

McCarthy ends by counseling states to exercise caution and avoid extending their powers too far in future international agreements involving climate change. However, she also encourages state support for the Paris Agreement, and emphasizes that U.S. participation is key for advancing climate justice and emissions reductions. Although it remains to be seen whether depending on state participation can meet the original U.S. target, states are in a good position to continue making progress in their own capacity.

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