• Federal Judge Aileen Cannon dismissed the criminal classified documents case against former President Donald Trump, saying the appointment of special counsel Jack Smith as prosecutor for the case violated the U.S. Constitution.
• Trump was accused in the Florida case of illegally retaining classified government documents after leaving the White House in January 2021, and trying to withhold them from government officials who sought their return.
• The ruling comes days after a would-be assassin narrowly missed killing Trump during a campaign rally in Pennsylvania, and hours before the start of the Republican National Convention.

Florida federal Judge Aileen Cannon on Monday in a stunning decision dismissed the criminal classified documents case against former President Donald Trump and two co-defendants, ruling that the appointment of special counsel Jack Smith as prosecutor for the case violated the appointments clause of the U.S. Constitution.

A spokesman for Smith said the Department of Justice later Monday had authorized the special counsel to appeal Cannon's decision tossing the case to the 11th Circuit U.S. Court of Appeals.

"The dismissal of the case deviates from the uniform conclusion of all previous courts to have considered the issue that the Attorney General is statutorily authorized to appoint a Special Counsel," said Smith's spokesman, Peter Carr.

Trump was accused in the case of illegally retaining hundreds of classified government documents at his Mar-a-Lago club in Florida after leaving the White House in January 2021, and trying to hide them from government officials seeking their return.

The bombshell ruling by Cannon — who was appointed to her judicial seat Trump — comes two days after a would-be assassin narrowly missed killing Trump during a campaign rally in western Pennsylvania.

Cannon's decision, which also tossed criminal charges faced by Trump's valet Walt Nauta and Mar-a-Lago worker Carlos De Oliveira, was issued hours before the start of the Republican National Convention in Milwaukee. That convention will formally confirm Trump as the GOP presidential nominee for November's election.

"The Clerk is directed to CLOSE this case," Cannon wrote in her ruling in U.S. District Court for the Southern District of Florida.

Smith's appeal of the ruling is likely to be resolved only after the presidential election, all but guaranteeing that Trump would not face trial until 2025 at the earliest.

If Trump is elected president in November, he could order his attorney general to dismiss the case, and another pending federal criminal prosecution in U.S. District Court in Washington, D.C., where Smith also is prosecuting him as special counsel.

Trump is charged in that second federal case with multiple felonies connected to his efforts to reverse his 2020 election loss to President Joe Biden.

Cannon's ruling on the legality of Smith's appointment is not binding on the judge in the D.C. case, Tanya Chutkan, but is certain to be cited by Trump's lawyers there in a renewed effort to get that election case tossed out.

Chutkan also still needs to rule on issues in the case in light of a dramatic ruling on July 1 by the Supreme Court that found Trump had presumptive criminal immunity for official acts he performed as president. It is not clear yet how that ruling will affect the election case against him.

The question of the legality of Smith's 2022 appointment by Attorney General Merrick Garland is likely to end up before the U.S. Supreme Court.

Cannon in her ruling in the Florida case granting a dismissal motion by Trump's attorneys found that Smith's position violated the Constitution's appointments clause, which says "Officers of the United States" must be appointed by the president and confirmed by the U.S. Senate.

She also ruled that Smith's use of "permanent indefinite appropriation" — funding for his office — violated that constitutional clause.

"Both the Appointments and Appropriations challenges as framed in the Motion raise the following threshold question: is there a statute in the United States Code that authorizes the appointment of Special Counsel Smith to conduct this prosecution?" Cannon wrote. "After careful study of this seminal issue, the answer is no."

"The bottom line is this: The Appointments Clause is a critical constitutional restriction stemming from the separation of powers, and it gives to Congress a considered role in determining the propriety of vesting appointment power for inferior officers," the judge wrote.

"The Special Counsel's position effectively usurps that important legislative authority, transferring it to a Head of Department, and in the process threatening the structural liberty inherent in the separation of powers."

The ruling is just the latest in a series of controversial decisions by Cannon that favored Trump.

Trump in a social media post responding to the ruling, wrote, "As we move forward in Uniting our Nation after the horrific events on Saturday, this dismissal of the Lawless Indictment in Florida should be just the first step, followed quickly by the dismissal of ALL the Witch Hunts — The January 6th Hoax in Washington, D.C., the Manhattan D.A.'s Zombie Case, the New York A.G. Scam, Fake Claims about a woman I never met (a decades old photo in a line with her then husband does not count), and the Georgia 'Perfect' Phone Call charges."

"The Democrat Justice Department coordinated ALL of these Political Attacks, which are an Election Interference conspiracy against Joe Biden's Political Opponent, ME," Trump wrote in the Truth Social post.

Christopher Kise, a lawyer for Trump, in a statement, said, "Judge Cannon today restored the rule of law and made the right call for America.  Jack Smith is not above the law and must be held accountable under the Constitution."

"From the outset, the Attorney General and Special Counsel have ignored critical constitutional restrictions on the exercise of the prosecutorial power of the United States.  The Special Counsel has conducted a baseless, lawless, and politically motivated prosecution against President Trump," Kise said. "Judge Cannon made a courageous and correct decision. Jack Smith must now respect the rule of law, shut down his office, and end this unconstitutional abuse of power."

Senate Majority Leader Chuck Schumer, a New York Democrat, blasted the ruling and Cannon.

 "This breathtakingly misguided ruling flies in the face of long-accepted practice and repetitive judicial precedence," Schumer said in a statement.

"It is wrong on the law and must be appealed immediately. This is further evidence that Judge Cannon cannot handle this case impartially and must be reassigned," Schumer said. 

In addition to the two federal criminal cases, Trump is charged in a state case in Georgia with racketeering related to his attempts to reverse his 2020 electoral loss.

And he is awaiting criminal sentencing in New York state court after being convicted this year of crimes connected to a 2016 hush money payment by his then-lawyer to porn star Stormy Daniels.

— Additional reporting by CNBC's Kevin Breuninger.