(CNN) — A federal judge on Monday dismissed the classified documents case against Donald Trump, a shock ruling that clears away one of the major legal challenges facing the former president.

In a 93-page ruling, District Judge Aileen Cannon said the appointment of special counsel Jack Smith violated the Constitution. She did not rule on whether Trump’s alleged mishandling of classified documents was proper or not.

“In the end, it seems the Executive’s growing comfort in appointing ‘regulatory’ special counsels in the more recent era has followed an ad hoc pattern with little judicial scrutiny,” Cannon wrote.

The ruling by Cannon, a judge Trump appointed in 2020, comes on the first day of the Republican National Convention and as the nation reels from the failed attempt on Trump’s life over the weekend. Even though a trial before the presidential election was considered highly unlikely, many legal experts had viewed the classified documents case as the strongest one of the four cases that were pending against the former president.

Trump on Truth Social said the dismissal “should be just the first step” as he called for the other cases facing him also to be dismissed, claiming that the charges were “political attacks.”

The White House referred requests for comment to the Justice Department. Smith’s office has not responded to a call for comment.

Smith had charged Trump last year with taking classified documents from the White House and resisting the government’s attempts to retrieve the materials. He pleaded not guilty.

In a separate criminal case brought by Smith against Trump in Washington, DC, the special counsel was pursuing federal charges stemming from Trump’s attempts to overturn the results of the 2020 election. Trump also faces a state-level election subversion case in Georgia and he was convicted of state crimes in New York earlier this year for his role in a hush money payment scheme before the 2016 election.

Trump’s efforts to dismiss the case under the appointments clause was seen as a long shot, as several special counsels – even during his own presidential administration – were run the same way.

But the fringe argument gained steam when Supreme Court Justice Clarence Thomas threw his support behind the theory, writing in a footnote in the high court’s presidential immunity decision that there are “serious questions whether the Attorney General has violated that structure by creating an office of the Special Counsel that has not been established by law. Those questions must be answered before this prosecution can proceed.”

Still, Cannon held a hearing on the issue several weeks ago, pushing attorneys to explain exactly how Smith’s investigation into Trump was being funded. The judge’s questions were so pointed that special counsel attorney James Pearce argued that, even if Cannon were to throw out the case due to an appointments clause issue, the Justice Department was “prepared” to fund Smith’s cases through trial if necessary.

Cannon said in her order that the special counsel’s position “effectively usurps” Congress’ “important legislative authority” by giving it to the head of a department – DOJ, in this case – to appoint such an official.

“If the political branches wish to grant the Attorney General power to appoint Special Counsel Smith to investigate and prosecute this action with the full powers of a United States Attorney, there is a valid means by which to do so,” she wrote.

Could case be revived?

Cannon said in her ruling Monday that the Justice Department “could reallocate funds to finance the continued operation of Special Counsel Smith’s office,” but said it’s not yet clear whether a newly-brought case would pass legal muster.

“For more than 18 months, Special Counsel Smith’s investigation and prosecution has been financed by substantial funds drawn from the Treasury without statutory authorization, and to try to rewrite history at this point seems near impossible,” Cannon wrote. “The Court has difficulty seeing how a remedy short of dismissal would cure this substantial separation-of-powers violation, but the answers are not entirely self-evident, and the caselaw is not well developed.”

She noted in her ruling that Smith’s team “suggested” at a court hearing on the matter that they could restructure the office’s funding to satisfy her concerns.