"When the Biden administration proposes its anticipated new greenhouse gas rule for power plants, it will be one of the most consequential climate regulations in the United States.

To ensure that the pivotal rule holds up in court, however, Biden’s EPA must avoid the pitfalls that plagued the regulation’s predecessors, legal experts say.

Chief among those stumbling blocks is the definition of the “best system of emission reduction” under the Clean Air Act — a thorny issue that stoked fierce debate among lawyers, judges and lawmakers following the release of the Obama-era Clean Power Plan and the Trump administration’s subsequent Affordable Clean Energy rule.

“I’m not really in the position to suggest what the best system of emission reduction should be,” said Kevin Minoli, a partner at the law firm Alston & Bird. “But I know that it’s something that the agency is going to have to very thoroughly understand and deal with upfront if it wants to survive a judicial challenge on the back end.”"

Maxine Joselow and Niina H. Farah report for E&E News August 2, 2021. [2]