The American Petroleum Institute (API) made its first foray into the legal battle over an Obama-era rule governing hydraulic fracturing (fracking) on public and tribal lands, asking a federal district court in San Francisco to allow it to intervene in a pair of lawsuits filed after the Trump administration rescinded the rule.

Last Friday, API filed motions to intervene in two cases in U.S. District Court for the Northern District of California. The lawsuits, brought by California Attorney General Xavier Becerra and a coalition of environmental groups, were each filed on Jan. 24.

At issue is a decision by the Interior Department’s Bureau of Land Management (BLM) to rescind the fracking rule last December. BLM first unveiled the rule in 2015.

According to court records, the Independent Petroleum Association of America (IPAA) and the Western Energy Alliance (WEA) filed motions to intervene on Feb. 22. API’s filing on Friday lists IPAA and WEA as proposed intervenors.

API’s filing also indicated that although the federal government did not oppose the intervention, the plaintiffs agreed to allow the trade association to intervene on the condition that it file consolidated briefs with IPAA and WEA. When API refused, the plaintiffs said they opposed allowing it to intervene.

“API’s members will be directly damaged if the invalidated provisions of the fracking rule were to take effect, because those provisions impose expensive, arbitrary and duplicative regulatory burdens on API members that own or operate federal and Indian oil and gas leases and require in many cases costly and permanent capital modifications to infrastructure,” API said in its filing. “Imposing the requirements of the fracking rule would also jeopardize the legally-protected confidentiality of sensitive commercial information related to hydraulic fracturing fluid composition and use.”

API also argued that the BLM, IPAA and WEA cannot adequately represent its interests.

The plaintiffs in both cases urged the court to vacate the rescission and issue a mandatory injunction compelling the Trump administration to reinstate the 2015 rule in its entirety.

The Trump administration formally rescinded the rule on Dec. 28. One day earlier, a three-judge panel of the U.S. Court of Appeals for the Tenth Circuit, ruled against rehearing arguments. Although the panel didn’t specify why it had denied a rehearing, the same panel last September cited Trump’s election and the subsequent redirection of the BLM toward rescission.

A district court judge in Wyoming ruled in June 2016 that the BLM did not have the authority to regulate fracking.

The cases are Sierra Club et al v. Ryan Zinke et al, No. 4:18-cv-00524; and State of California v. BLM et al, No. 4:18-cv-00521. District Court Judge Haywood Gilliam Jr. is presiding over both cases.