A federal judge cleared the way Monday for the attorneys general of Maryland and the District of Columbia to begin issuing subpoenas in their lawsuit alleging that President Donald Trump has violated a constitutional prohibition on gaining financially from his position by doing business with foreign governments.

A list of subpoenas was expected to be made available Tuesday, according to a spokeswoman for D.C. Attorney General Karl Racine.

“Huge step forward in our emoluments case,” Maryland Attorney General Brian Frosh tweeted. “Judge issues scheduling order. We can now move forward and get the evidence to prove our case.”

The case centers on foreign dignitaries paying to stay at the luxury Trump International Hotel in Washington. Frosh and Racine say Trump’s ownership of a business that accepts money from foreign governments violates the U.S. Constitution’s emoluments clause.

U.S. District Judge Peter J. Messitte issued an order Monday beginning the case’s discovery phase. In discovery, each side can request that the other answer specific questions or produce documents.

“We will now serve subpoenas to third-party organizations and federal agencies to gather the necessary evidence to prove that President Trump is violating the Constitution’s emoluments clauses — our nation’s original anti-corruption laws,” Racine said in a statement.

The judge’s order means the Trump Organization could be required to disclose sensitive documents.

“We are entitled to know every payment the president received from a foreign government, from a state government — whatever benefits he received,” Frosh said in an interview earlier this year. “That could include financing.”

The U.S. Justice Department, which is defending Trump, has sought to stay the court’s proceedings while it appeals its denial of a motion to dismiss the case.

“Accordingly, the president does not believe that discovery should commence now, but should await the Court of Appeals’ resolutions,” Justice Department attorneys wrote in a motion filed Friday.

But Messitte issued the schedule Monday, ordering discovery to proceed into next summer.

Justice Department communications officials declined Monday to comment on the decision.

Frosh filed the suit with Racine in June 2017. Both are Democrats; Trump is a Republican.

The framers of the Constitution adopted the emoluments clause out of concern that foreign heads of state could exert influence over the president or other federal officials.

In March, the judge declined to dismiss the case after the Justice Department argued the plaintiffs did not have standing to sue because they could not clearly show how residents of Maryland and the District of Columbia had been harmed by the payments.

Maryland has said its commercial interests — such as competing hotels — could be harmed by any advantage the Trump hotel enjoys through its association with the president.