Environmental Protection Agency Administrator Scott Pruitt holds a hard hat he was given during a visit to a Sycamore, Pa., coal mine. (Gene J. Puskar/AP)

In his drive to dismantle President Barack Obama’s regulatory legacy, President Trump has signed executive orders with great fanfare and breathed life into a once-obscure law to nullify numerous Obama-era regulations.

But his administration is also using a third tactic: Going to court to stop federal judges from ruling on a broad array of regulations that are being challenged by Trump’s own conservative allies.

These cases were filed long before the election. Now, Trump administration officials, eager to flip the government position, want judges to put the cases on hold and give federal agencies time to revise or shrink the Obama-era regulatory regime.

Trump officials are also asking judges to keep any existing stays in place so that the contested regulations do not go into effect while the new administration considers its deregulatory strategy.

Much is at stake. The Environmental Protection Agency persuaded an appeals court to give it a chance to revise existing limits on street-level smog. The EPA also wants a court to let it rewrite the Clean Power Plan that Obama showcased at the 2015 Paris climate conference. And the Justice Department has sought to review a Department of Health and Human Services regulation that prohibits health-care providers from discriminating against people on the basis of gender identity, sex stereotyping or the termination of a ­pregnancy.

How Trump is rolling back Obama’s legacy

The legal strategy is a critical part of the administration’s battle to reverse rules enacted in the final years of Obama’s tenure.

For the Trump administration, getting the regulations back for reconsideration is also the surest way to stave off court rulings — especially those from liberal-leaning benches — that could hinder its ability to unwind rules adopted by the previous administration.

“If the courts uphold the previous administration, you still have the discretion to change things, but you’ve lost the argument that you were forced to do it or that the previous administration exceeded legal bounds,” said Richard Lazarus, a law professor at Harvard University. He said that if Trump officials “were confident the courts would rule against” the Obama rules, “you wouldn’t see them trying to hold cases in abeyance.”

While some presidents — including Obama — have used this legal tactic in the past, Trump has expanded on the strategy.

When Obama took office, his administration asked federal courts to hold in abeyance at least half a dozen cases regarding EPA regulations and permits, saying it needed more time to decide whether to defend, revoke or revise the matters.

This time, however, EPA Administrator Scott Pruitt is calling on courts to send back rules that he had sought to overturn while serving as Oklahoma’s attorney general before taking up his current post two months ago.

“The Trump team is trying a shortcut,” said David Doniger, an attorney with the Natural Resources Defense Council who has been a leading defender of the Clean Power Plan. He said that because the Supreme Court has issued a stay in the power plan case, the Trump administration could effectively kill the plan with a prolonged reconsideration without going through the established guidelines for undoing a rule.

A tactic used before

But administration backers note that Democrats and Republicans alike have deployed this legal strategy.

“This is actually pretty routine,” Jeffrey R. Holmstead, a lawyer at the Bracewell law and lobbying firm and an EPA official under President George W. Bush, said in an email. “When the Obama Administration [officials] took office, there were a number of Bush Administration rules being challenged that they didn’t want to defend.”

Lawyers on both sides say fundamental principles are at stake. Before Trump’s election, lawyers for the states challenging the Clean Power Plan said that basic federalism meant that the federal government cannot compel states to undertake potentially costly energy programs. But lawyers for environmental groups say legislation adopted by Congress gives the federal government the power and obligation to set limits on emissions from power plants while paying attention to states’ rights in designing plans to carry that out.

Some liberals have used federalist arguments to block Trump initiatives, such as the Trump administration’s efforts to compel cities to implement immigration laws by threatening to cut their federal funding.

In some cases, the Trump administration has made a court case moot, such as when the Justice and Education departments rescinded guidance that informed school districts that they had to accommodate students’ access to facilities based on their chosen gender identities.

In another case, the Justice Department asked the U.S. Court of Appeals for the 5th Circuit on April 4 for more time to respond to a lawsuit challenging the HHS regulation on health-care providers and discrimination.

The rule reflects the previous administration’s interpretation of Section 1557 of the Affordable Care Act and was challenged by five states as well as several religious groups who said it represented federal overreach and should have included a carve-out for religiously affiliated medical providers.

A federal judge in Texas stopped two provisions of the rule, pertaining to gender identity and the termination of a pregnancy, from taking effect Jan. 1, while other aspects of it were allowed to go forward.

“Certainly, asking for additional time can be a very strong signal that the administration intends to change course on the subject of litigation,” said Sarah Warbelow, legal director of the Human Rights Campaign. “That’s very concerning to us.”

The most frequent use of the strategy involves Obama-era environmental regulations.

The Clean Power Plan court battle is one of the highest-profile cases. The plan was issued by the Obama administration EPA on Aug. 3, 2015. A group of 28 states — led by Pruitt — sued to block the plan, and that case has been argued before a full 10-member panel of the liberal-leaning U.S. Court of Appeals for the District of Columbia Circuit. On Feb. 9, 2016, the Supreme Court issued a stay preventing the plan from going into effect while it makes its way through the appeals court.

Now the EPA wants the appellate court to hand the regulation back without ruling on it.

“They’ve filed a motion asking the ten-judge panel to hold the case in ‘abeyance’ — i.e., put it in the deep freeze — and thus not to issue its decision, until the Administration is done with its multi-year review and rulemaking,” Doniger said. “They’re saying whatever you do, don’t decide anything.”

Deadlines spur action

Pressing deadlines have pushed the administration to take action.

On April 11, the U.S. Court of Appeals for the District of Columbia Circuit granted the EPA’s request to delay a long-scheduled April 19 hearing in cases challenging standards used to limit ground-level ozone, which is formed when emissions from industrial facilities and vehicles interact with sunlight and is linked to lung and heart ailments, including asthma.

“We are thankful to the court for granting our motion to postpone oral argument,” EPA spokeswoman Liz Bowman said in an email, adding that it would allow the agency to ensure the rule’s “broad implications . . . in light of President Trump’s pro-growth agenda.”

The EPA has also asked a three-judge appeals court panel to hold in abeyance a challenge to the agency’s rules that new power plants meet carbon dioxide emissions standards. A Trump executive order directs the EPA to rewrite that standard. Oral arguments scheduled for April 17 were postponed.

The EPA rule designed to stop the pollution of tributaries of major rivers is in the Court of Appeals for the 6th Circuit. The Obama administration already filed a brief in the case, a roughly 170-page defense of the law and science that it said justified the rule. The case was postponed because the Supreme Court wanted to rule on a narrow jurisdictional issue. Here, too, the Trump EPA wants to “review and rescind or revise” the rule.

The Interior Department indicated in court filings in mid-March that it planned to withdraw a 2015 rule restricting hydraulic fracturing on federal and tribal lands, which had been stayed in court; less than two weeks later, Trump issued an executive order calling for the rule to be rewritten.

While some departments, such as the EPA and Interior, have asked the courts to return contested rules to them so they can take a second look, others — including the Labor Department, which still does not have a secretary in place — have not.

Many business officials, who have challenged some of the Obama-era rules, said they support the new administration reclaiming the regulations.

“If the courts rule in favor of the rule that was issued [under Obama], it would be allowed to go into effect,” said Dan Bosch, senior manager of regulatory policy for the National Federation of Independent Business, in an interview.

Bosch noted that not only would his group’s members have to start spending money to comply with the existing rule, but also, “at that point, it’s a lot harder to make it go away.”

David Weil, who headed the Labor Department’s wage and hour division under Obama, said in an interview that he hoped the legal challenge to the federal overtime rule continued because he believed it would be upheld. That rule, which was issued last year, is subject to a nationwide injunction.

“I do feel very confident in the regulation,” said Weil, now a Boston University professor of management. “It was a responsible use of our regulatory authority.”