They say that timing is everything. On Tuesday, with one day remaining of the Trump administration, a federal appeals court struck down the signature piece of the administration’s climate regulation. Known as the Affordable Clean Energy rule (or ACE), the rule was intended to replace the Obama administration’s proposed Clean Power Plan rule (CPP), which sought to reduce greenhouse gas emissions from American power plants.

ACE was a kind of scaled down version of the CPP, including ways to reduce emissions at existing fossil fuel power plants but eliminating the CPP’s broader efforts to shift generation away from those plants altogether in favor of alternate clean energy sources. The Trump administration argued that these broader efforts went beyond the legal authority to regulate power plant emissions granted by the Clean Air Act (ACE also used a less pessimistic—and as it turns out more realistic—baseline for projecting future emissions). A majority of the D.C. Circuit panel disagreed, and sent the rule back to the Environmental Protection Agency (EPA) for reworking.

Given the switchover from the Trump to the Biden administration, ACE was not long for this world in any case. The decision does make it somewhat easier for the new administration to scrap the rule and replace it with something else. But it will still take time to come up with a third try at a climate regulation for existing power plants, and whatever it develops will still face years of limbo as the inevitable legal challenges are worked out.

And at the end of that road is the Supreme Court. As I’ve written before, it’s unlikely that there are five votes on the Supreme Court to sustain an ambitious climate rule, or possibly any climate rule at all. On that score, the separate opinion in the case by Judge Justin Walker is worth noting. Judge Walker agreed with the rest of the panel that ACE should be invalidated, but he did so on the grounds that both the Trump and Obama climate rules exceeded EPA’s legal authority. His argument involves a technical matter of statutory interpretation that I raised over six years ago when the CPP was first announced, and is one of several possible avenues a Supreme Court majority could well take in striking down whatever eventual replacement rule the Biden administration comes up with. The new Biden EPA may find itself in the unenviable position of having to spend years working on a rule that it knows is almost certain to be struck down.

And in the meantime, we will continue with no rule in place. But, somewhat paradoxically, that might not matter. The CPP never went into effect, but the United States ended up meeting its emission reduction goals anyway (and a decade early to boot). Even before the pandemic, the carbon intensity of the economy was declining more under the Trump administration than during Obama’s second term. Regardless of what happens in Washington, these largely market driven reductions in power sector emissions are likely to continue.

Image credit: hrui