The Legal Foundation of US Climate Policy Under Threat

Buried beneath the daily torrent of political news is a regulatory battle that could have more lasting environmental consequences than almost any other action taken by the current administration. The Trump White House is moving to dismantle the Environmental Protection Agency's endangerment finding, a 2009 scientific and legal determination that forms the bedrock of virtually all federal climate regulation in the United States.

For most people, the endangerment finding is an obscure piece of bureaucratic machinery. But for environmental lawyers, climate scientists, and the fossil fuel industry alike, it is the single most important regulatory document in American environmental policy. Understanding what it is and why its elimination matters requires a brief journey into the intersection of science, law, and politics.

What Is the Endangerment Finding?

In 2007, the Supreme Court ruled in Massachusetts v. EPA that greenhouse gases qualify as air pollutants under the Clean Air Act and that the EPA was obligated to determine whether they endanger public health and welfare. After an exhaustive review of the scientific literature, the EPA issued its endangerment finding in December 2009, concluding that six greenhouse gases, including carbon dioxide and methane, do indeed pose a threat to human health and the environment.

This finding did not itself impose any regulations. Instead, it established the legal predicate for the EPA to regulate greenhouse gas emissions under the Clean Air Act. Every major climate regulation issued by the federal government since 2009, from vehicle fuel efficiency standards to power plant emission limits, traces its legal authority back to this determination.

  • The finding covers six greenhouse gases: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride
  • It was based on a comprehensive review of peer-reviewed scientific literature
  • The Supreme Court upheld the EPA's authority to make such a determination
  • It serves as the legal foundation for all federal greenhouse gas regulations

Why the Administration Wants It Gone

For opponents of climate regulation, the endangerment finding has long been the white whale. Repealing individual regulations is a game of whack-a-mole because courts can order the EPA to issue new ones as long as the underlying finding stands. But eliminating the finding itself would pull the legal rug out from under the entire framework of federal climate regulation in one stroke.

The administration argues that the original finding was based on flawed science and that the economic costs of the resulting regulations outweigh any environmental benefits. Industry groups have supported the effort, arguing that climate regulation puts American businesses at a competitive disadvantage.

The Scientific and Legal Obstacles

Reversing the endangerment finding is not as simple as issuing an executive order. The Clean Air Act requires that the EPA's determination be based on scientific evidence, and the overwhelming consensus of climate science has only strengthened since 2009. To legally rescind the finding, the EPA would need to demonstrate that the scientific basis for it has changed, a task that virtually no credible climate scientist believes is possible.

Environmental groups have already signaled that they will challenge any attempt to revoke the finding in court, and legal experts say the administration faces an uphill battle. Federal courts have consistently upheld the scientific basis of the finding, and reversing it would require the EPA to essentially argue against the consensus of its own scientific staff.

The Environmental Consequences

If the administration succeeds, the consequences for climate policy would be profound. Without the endangerment finding, the EPA would lose its legal authority to regulate greenhouse gas emissions under the Clean Air Act. This would affect everything from tailpipe emission standards for vehicles to methane regulations for oil and gas operations to carbon dioxide limits for power plants.

Climate advocates warn that eliminating the finding would set back US climate efforts by decades and undermine the country's credibility in international climate negotiations. The United States is the world's second-largest emitter of greenhouse gases, and its regulatory posture has significant influence on global climate ambitions.

A Defining Moment for Environmental Law

The fight over the endangerment finding represents a collision between political will and scientific consensus. Its outcome will determine not just the trajectory of American climate policy but the broader question of how much weight scientific evidence carries in federal regulatory decisions. For the environment, the stakes could hardly be higher.