In the next few years, the International Maritime Organization will create the world’s first greenhouse gas (GHG) pricing mechanism to reduce emissions from shipping. The United States may be unable to adopt it legislatively, repeating the events of the Kyoto Protocol. To ease passage, nations agreed to create the mechanism as an amendment to the existing Convention for the Prevention of Pollution From Ships (MARPOL), which a U.S. Secretary of State should be able to unilaterally accept or reject under the expedited amendment procedure of MARPOL’s implementing legislation. This Article demonstrates the insufficiency of this strategy, as the procedure is unbounded and the pricing scheme too extraordinary, such that its usage may easily run afoul of the nondelegation doctrine and the new “major questions doctrine.” If the amendment instead were implemented by the U.S. Environmental Protection Agency through a Clean Air Act §115 finding, the executive may still be able to accept and implement the scheme, avoiding congressional gridlock.

In 2009, the U.S. Environmental Protection Agency (EPA) published what is commonly referred to as the “endangerment finding.” Prompted by the U.S. Supreme Court’s landmark decision in Massachusetts v. Environmental Protection Agency (2007) and reflecting robust science, the finding determined that six key greenhouse gases qualify as air pollution under the Clean Air Act and pose a threat to the health and welfare of future generations. This authorized EPA to set emissions standards for motor vehicles and other major sources of greenhouse gases; however, the Agency recently announced the finding will undergo reconsideration of whether it “complies with the law and is based on sound science and policy.” On May 22, 2025, the Environmental Law Institute hosted a panel of experts to discuss the legal and scientific foundations of the endangerment finding. Here, we present a transcript of that discussion, which has been edited for style, clarity, and space considerations.