“When it comes to restoring the vast majority of this Obama environmental policy, the rollbacks have actually been brought about by the introduction of new regulations,” said Jeffrey Holmstead, an attorney who represents fossil fuel companies in both Bush administrations at the EPA were active. “In some cases it took two to three years. They have to be replaced by new regulations. There is a legal process that must be followed. “

The reinstatement of the federal government’s broader regulations on air, water and climate pollution will take even longer. One main reason, legal experts said: When the Trump administration withdrew these rules, they almost never completely eliminated them. Rather, they are replacing strict federal pollution regulations with new, weaker pollution regulations.

For its part, the Biden government will try to legally reverse these weak regulations and replace them with stricter ones. And this legal process usually takes two years or more. For example, the Trump EPA overturned the Obama administration’s largest single policy to curb climate change, a rule that forced automakers to rapidly increase the fuel economy of passenger cars, drastically reducing their heat-storing carbon pollution. To do this, the EPA had to go a long way in law, formally publish a proposal to change the rule, open it to public comment, develop legal, economic and scientific justifications for the rule, and perform complex technical analyzes of the effects of the new rule on traffic safety, air quality and consumer behavior.

Although the Trump administration began withdrawing the Obama auto-pollution rule in the first few days of taking office, it wasn’t finalized until last spring.

The same schedule could be waiting for Mr Biden when he tries to reintroduce the rule.

“It’s a tedious, time-consuming process,” said Richard Revesz, professor of environmental law at New York University, who was shortlisted by Mr. Biden to head the EPA

“Nobody questions the authority of the EPA to reinstate these auto-pollution regulations,” Revesz said. “But they can’t just make sure that the Trump rules are dropped by order of the executive. You have to follow the same process – prepare all scientific and economic analyzes, and you have to do everything right. “