WASHINGTON — The federal judge presiding over the classified documents case against former U.S. President Donald Trump in Florida dismissed the prosecution on Monday, siding with defence lawyers who said the special counsel who filed the charges was illegally appointed by the Justice Department.

The decision by U.S. District Judge Aileen Cannon, which can be appealed and may be overruled by a higher court, brings at least for now a stunning and abrupt conclusion to a criminal case that at the time it was filed was widely regarded as the most perilous of all the legal threats the Republican former president confronted.