A federal judge in Washington, D.C., has ruled President Donald Trump's longtime accounting firm must turn over years of his financial records to the U.S. House of Representatives, upholding a Congressional subpoena that demanded those documents.

The ruling from U.S. District Judge Amit Mehta delivered a major blow to Trump in what marks the first time a federal court has waded into the continued standoff between the president and Democratic lawmakers. Lawyers for Trump filed the lawsuit last month seeking to block his accountant, Mazars USA LLP, from complying with a House Oversight committee's subpoena.

“Courts have grappled for more than a century with the question of the scope of Congress's investigative power. The binding principle that emerges from these judicial decisions is that courts must presume Congress is acting in furtherance of its constitutional responsibility to legislate and must defer to congressional judgments about what Congress needs to carry out that purpose. To be sure, there are limits on Congress's investigative authority. But those limits do not substantially constrain Congress. So long as Congress investigates on a subject matter on which 'legislation could be had,' Congress acts as contemplated by Article I of the Constitution,” Mehta wrote.