The House Committee on Education and Labor filed a subpoena against the National Labor Relations Board on Tuesday for records about potential conflicts of interest among board members, which the committee has been seeking.

The legal request comes after more than a year of attempts by the committee to acquire ethics related documentation from the NLRB — the federal body charged with upholding workers’ rights to organize and raise safety concerns — on issues that involve an NLRB board member’s former law firm.

Committee chairman Rep. Robert C. “Bobby” Scott (D-Va.) said that the board’s ongoing refusal to provide the documents suggests that the board is covering up malfeasance, according to a letter from Scott to the panel to NLRB Chairman John Ring.

“[T]he continued refusal to give the Committee certain documents indicate that the NLRB has something to hide regarding decisions that are likely tainted by a defective process, such as the McDonald’s case and the joint employer rulemaking,” Scott wrote in the letter, sent earlier this month. “The Committee is left to conclude that the NLRB’s sole motivation for refusing to produce requested documents is to cover up misconduct.”

The NLRB says that though it has not given the documentation over, it has offered the committee the ability to review some of the documents in private.

“The Committee knows it is not entitled to the documents it is demanding,” Ring said in a statement. “This is a made-up controversy solely for political theater."

A spokesman for the NLRB called the subpoena “unprecedented," in a statement, adding the “disclosure of these pre-decisional documents would discourage agency employees from providing candid advice and undermine the internal deliberations of the Board.”

The Committee disagrees, saying that it is entitled to the information that is being shielded from it.

The National Labor Relations Board is made up of four members currently, three Republicans and one Democrat, all Trump appointees. The panel has pivoted and issued far more employer-friendly rulings since the Obama administration. The White House has not appointed anyone to the fifth seat, which would typically be taken up by a Democrat.

The documentation requested by the committee involves the issue of joint employer classification, which is an issue when there is more than one employer involved, such as when one of the employers is a franchise. Joint employer labor issues could have implications for millions of workers at large corporations like McDonald’s.

The NLRB, under President Barack Obama, focused on making it easier for workers to hold joint-employers accountable for their working conditions — such as workers who work for McDonald’s franchisees seeking redress from the McDonald’s Corp. But the Trump administration has worked to narrow these protections.

The first case the committee has sought more information on was a decision made by the NLRB in December to approve a settlement between McDonald’s franchisees and workers that absolved McDonald’s from direct responsibility over workers, as a joint employer — a legal win for the company.

William Emanuel, an appointee to the board by President Trump, was asked to recuse himself by the workers’ lawyers, because he worked for a law firm that had helped set up a hotline for McDonald’s franchise owners to call for legal advice about how to respond to some of the protests by workers, according to the committee and Bloomberg Law.

Emanuel participated in the McDonald’s decision — a violation of an executive order that prohibits appointees from participating in any matter that is “directly and substantially related” to former employers or former clients, said Josh Weisz, a spokesman for the House Education Committee.

The committee is also seeking information about Emanuel’s involvement in the board’s rulemaking process on the joint employer issue, which limited workers ability to hold joint employers accountable back in February.

The committee also wants more information on the NLRB’s decision to hire a contractor to sort and categorize public comments on the joint-employer rulemaking process.

The NLRB board disagrees that its members have been involved in any conflict of interests.

“There is absolutely no evidence that Member Emanuel’s participation violated any ethical standards,” said NLRB spokesman Edwin W. Egee in his statement. “To the contrary, the Board has protocols in place to ensure that Members do not violate their ethical obligations. Those protocols were not violated in either the Joint Employer Rulemaking or McDonald’s.”

The subpoena is the latest legal maneuver in the bitter struggle between the Democratic House and the Trump administration over the last year and a half. Legal fights have broken out after the Trump administration has refused information and official testimony on topics like Trump’s financial dealings, the call between Trump and Ukrainian President Volodymyr Zelensky that sparked the impeachment inquiry, and the U.S. Postal Service’s election year mail slowdown.

This story has been updated to reflect the subpoena has been filed.