A federal district judge has told the accounting firm Mazars it will need to turn over Donald Trump's accounting records from before he was President to the Democratic-controlled House Oversight Committee.
In a 41-page opinion, Judge Amit Mehta of the DC District Court dealt a significant blow to the White House as he rejected Trump's attempt to block the committee's subpoena, asserting that Congress is well within its authority to investigate the President.
Mehta's writings will likely be more fodder for other judges to consider as Trump and his Cabinet try to hold off Congress from getting the President's business records, such as through the IRS, banks and in other court fights.
Already, the House of Representatives has flagged the ruling to a judge in New York, where another court is considering challenges to House subpoenas to Deutsche Bank and Capitol One for more Trump records.
Congress specifically can probe the President for conflicts of interest and ethical questions, Mehta wrote, reaching into history -- citing everything from the presidency of James Buchanan, to the Teapot Dome scandal, to Watergate and Whitewater -- to back up his ruling.
"History has shown that congressionally-exposed criminal conduct by the president or a high-ranking Executive Branch official can lead to legislation," Mehta wrote.
"It is simply not fathomable that a Constitution that grants Congress the power to remove a president for reasons including criminal behavior would deny Congress the power to investigate him for unlawful conduct -- past or present -- even without formally opening an impeachment inquiry," he added.
Trump's legal team plans to appeal, a person familiar with the case said Monday.
Mehta's opinion, coming not even a week after a hearing in the case, will kickstart a race to appeals courts.
Mazars won't have to turn over the subpoena for another seven days, according to the judge, but other courts will have to step in to stop the accounting firm from complying with Congress after that.
"The court is well aware that this case involves records concerning the private and business affairs of the President of the United States. But on the question of whether to grant a stay pending appeal, the President is subject to the same legal standard as any other litigant that does not prevail," Mehta wrote.
The House Oversight Committee subpoena of Mazars seeks a vast amount of communications and financial records related to the firm's work for Trump himself, as well as his businesses and foundation from 2011 through 2018.
Mazars became a target in the House investigation after former Trump personal attorney Michael Cohen accused the President of fudging his wealth in an unsuccessful attempt to buy the Buffalo Bills football team and reduce his real estate tax burden.
Oversight committee Chairman Elijah Cummings called the ruling a "resounding victory for the rule of law and our Constitutional system of checks and balances."
"The court recognized the basic, but crucial fact that Congress has authority to conduct investigations as part of our core function under the Constitution," the Maryland Democrat said in a statement.
Trump immediately called the ruling "crazy."
"We disagree with that ruling, it's crazy," Trump told reporters Monday evening before departing the White House for a rally in Pennsylvania, noting that Mehta was appointed by President Barack Obama.
"This never happened to any other president," he added, saying that Democrats are trying to "get a redo" on the investigation into Russian meddling in the 2016 election.
"The Democrats were very upset with the Mueller report, as perhaps they should be," the President said.
CNN's Nikki Carvajal contributed to this report.