The new climate agreement negotiated in Paris late last year marks a crossroads in international climate action. The Paris Agreement may provide for the robust but flexible tool to combat climate change that the global community has waited for. The agreement mandates establishment of specific emission reduction contributions by all major players, allows for countries to define their contributions independently, and requires them to report on their progress – including periodically returning to the negotiating table with more ambitious targets. US negotiators worked hard to help shape the new instrument into one that refrains from imposing absolute legally binding emission reduction targets and new financial commitments, in order to avoid consultations with a Congress fiercly opposed to international climate action. With the adoption of the Paris Agreement, President Obama has managed to lawfully bind the US to an agreement outside of the treaty process based on his own constitutional authority, existing UNFCCC obligations, and national law. Full implementation of the Paris Agreement in the United States is therefore realistic, but not free of obstacles.