An unprecedented private prosecution attempt can proceed against the politician, District Judge Margot Coleman said Wednesday. Johnson will be required to attend Westminster Magistrates Court for a preliminary hearing to answer allegations that he made false claims about British spending on the European Union, she said.

“The allegations which have been made are unproven accusations and I do not make any findings of fact,” the judge said.

The charges can only be dealt with in a higher criminal court, she said. It normally takes three to four weeks after a court summons is issued for an individual to appear. No date has yet been set for Johnson’s appearance.

The attempt to privately prosecute Johnson could be an embarrassment for the politician, who is the favorite to succeed Theresa May when she formally resigns as leader of the Conservatives and U.K. prime minister.

Campaigner Marcus Ball is trying to bring charges against the lawmaker over his “infamous” claim that the U.K. sent 350 million pounds ($442 million) per week to the EU — one of the central tenets of the Brexit campaign. Ball’s legal team said last week that Johnson had engaged in criminal behavior.

Johnson’s lawyer Adrian Darbishire said at an earlier hearing that it is “absolutely denied that he acted in an improper or dishonest manner at any time.” Lawyers for Johnson didn’t immediately respond to messages seeking comment Wednesday.

“This application is brought for political purposes,” Johnson’s legal team said last week, calling it a political stunt.

Ball, a 29-year-old former founder of technology companies, has been attempting to crowdfund the proposed prosecution. He said he’d considered various individuals from both sides of the Brexit debate before deciding on Johnson.

The 350 million-pound spending claim was painted on the side of a bus and cited repeatedly during the Brexit campaign. The core claim of the Vote Leave campaign was discredited during the campaign by the House of Commons Treasury Select Committee, which called it “highly misleading.”

“He knew the figure was wrong still he chose to repeat it over and over and over,” Lewis Power, a lawyer for the private prosecutor said last week. DM