Democratic members of Congress have standing to sue President Donald Trump for allegedly violating the foreign emoluments clause, a federal judge in Washington, D.C., ruled Friday afternoon, in a court win that clears a significant hurdle for the lawmakers.

The plaintiffs in Blumenthal v. Trump—201 members of Congress—will be able to proceed with their suit, after U.S. District Judge Emmet Sullivan of the District of Columbia denied in part Trump’s bid to dismiss the case for lack of standing.

“Plaintiffs adequately allege that the president has completely nullified their votes in the past because he has accepted prohibited foreign emoluments as though Congress had provided its consent,” Sullivan wrote. “And he will completely nullify their votes in the future for the same reason, as plaintiffs allege that he intends to continue this practice.”

The group of congressional Democrats, represented by Brianne Gorod and Elizabeth Wydra of the Constitutional Accountability Center, began its lawsuit against Trump last year, alleging that the president has violated one of the Constitution’s anti-corruption clauses by continuing to accept foreign gifts and benefits through his businesses, including hotels and golf courses.

They argued that because Trump, who continues to hold interests in and profit from his vast business empire, has accepted foreign emoluments, he has denied members of Congress their individual rights to vote on each emolument. The Constitution’s foreign emoluments clause requires the president to get congressional consent before accepting such gifts.

U.S. Sen. Richard Blumenthal, D-Connecticut, who was a lead plaintiff in the case, called Friday’s ruling “a major breakthrough.”

“It enables us to hold the president accountable for taking huge payments, benefits and gifts from foreign governments or powers, and that is a violation of the chief anti-corruption provision of the Constitution,” Blumenthal said.

U.S. Rep. Jerrold Nadler, D-New York, was the other lead plaintiff in the case.

Sullivan deferred ruling on three additional grounds for dismissal advanced by U.S. Department of Justice lawyers, who represent the Trump administration. One of the questions Sullivan must grapple with next includes the definition of an “emolument.” Still, Friday’s ruling was a boost for the plaintiffs on a threshold issue.

In court papers and during oral arguments in June, the Justice Department had contended that the court lacked jurisdiction to review the claims by the plaintiffs. The lawmakers, the United States argued, had not established sufficient injury.

But Sullivan was not persuaded to dismiss the suit for lack of standing.

He found on Friday that the plaintiffs “adequately” alleged an injury the courts could redress. He acknowledged the case raised a separation of powers question, but “plaintiffs have no adequate legislative remedy” and the courts could resolve the matter, he wrote.

“The president’s alleged acceptance of prohibited foreign emoluments as though Congress provided consent is indistinguishable from ‘treating a vote that did not pass as if it had, or vice versa,’” Sullivan’s 58-page opinion read. “[A]s soon as the president accepts a prohibited foreign emolument without obtaining congressional consent, his acceptance is irreversible.”

The president’s relationship with his businesses has been at the center of two other major emoluments-related lawsuits, in addition to the Blumenthal case.

In July, a federal judge in Maryland gave a greenlight to an emoluments lawsuit brought by a pair of state attorneys general, rejecting a narrow interpretation of the term “emoluments.”

Read the ruling here.