With the facts against it, the administration will have to argue the law. But that approach has already led to numerous lost deregulatory cases. At the Institute for Policy Integrity, which I direct at the New York University School of Law, we have kept a tally of court challenges to Trump-era deregulatory rules. The administration’s record is dismal: It prevailed in two cases and either lost or abandoned its position in 20 others.

So not only have the facts been against the government’s position. So has the law.

On the power plant emissions rule, the administration’s own analysis shows that its weaker regulatory scheme will be dramatically worse for the public. In fact, the administration’s so-called Affordable Clean Energy Rule is likely to increase overall emissions by creating new loopholes for coal plants to evade air pollution restrictions and operate more frequently. That will cause a significant increase in climate pollution and up to 1,400 additional American deaths per year, according to the government’s projections. The E.P.A. says that it is exercising its discretion in choosing this rule, which will impose tens of billions of dollars of net harms on the American people. This is a textbook example of “arbitrary and capricious” conduct — exactly what the law prohibits.

In weakening the vehicle emissions rule, the administration relies on economic and legal arguments that don’t stand up to scrutiny. The current standards require automakers to steadily increase the fuel efficiency of new passenger vehicles, limiting climate pollution while reducing consumer fuel costs.

The Trump administration has proposed freezing the standards in 2021 and revoking a waiver that allows California to set its own, more stringent vehicle pollution limits, which other states follow.

Officials claim the resulting increases in pollution and fuel costs are justified by supposed safety benefits from rolling back the standards. It assumes that stricter efficiency standards raise the price of vehicles. Standard economic theory predicts that people would then buy fewer cars because each car would be more expensive. But instead, the administration’s faulty analysis leads it, wholly implausibly, to the opposite conclusion: that people will buy more cars, and therefore drive more miles and have more accidents.