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.