In a flight of judicial activism historically decried by conservatives, the Supreme Court's conservative majority reached out on the last day of its 2021 term to decide a rule that was not before it, sidestepped the reasoning of the court below, and "stripped the [Environmental Protection Agency] of the power Congress gave it to respond to 'the most pressing environmental challenge of our time'" (West Virginia v. EPA, 597 U.S. __ (June 30, 2022) (dissent)).

The pertinent challenge was how to cost-effectively reduce billions of tons of greenhouse gases emitted each year by U.S. coal-fired electric power plants. The rule was the 2015 Clean Power Plan, which sought to place statewide caps on such emissions but allowed electric utilities to meet those caps by acquiring emission-reduction credits from lower-emitting gas-fired or renewable generating facilities. The vehicle the majority deployed to strike down that rule was a legal fiction which surfaced in the environmental sphere less than a decade ago (UARG v. EPA, 573 U.S. 302 (2014)), what the lower court called "the so-called 'major questions' [MQ] doctrine." MQ, derived from the principle that Congress cannot delegate pure legislative (as opposed to implementation) authority to the executive branch, asserts that "in extraordinary circumstances," where an agency such as the EPA "suddenly discovers" power to address "questions of vast social or economic importance," Congress must specifically have delegated it such regulatory authority.