Boris Johnson has been ordered to appear in court over claims he lied by saying the UK gave the EU £350m a week.
The Tory leadership candidate has been accused of misconduct in public office after making the claim during the 2016 EU referendum campaign.
It is a private prosecution launched by campaigner Marcus Ball, who crowdfunded £200,000 for the case.
Mr Johnson’s representatives have called the case a “stunt” that is being “brought for political purposes”.
The preliminary hearing will take place at Westminster Magistrates’ Court and the case will then be sent to the Crown Court for trial.
The BBC’s assistant political editor, Norman Smith, said the allegations could not come at a worse time for Mr Johnson, and his critics are likely to use the claims against him in the upcoming contest to become next Tory leader and prime minister.
The £350m figure was used by the pro-Brexit Vote Leave group throughout the referendum campaign on the side of a red bus, calling for the UK to “fund our NHS instead”.
Mr Johnson faces three allegations of misconduct in public office, between 21 February 2016 and 23 June 2016 – after he had announced he was backing Leave, up until the referendum vote – and 18 April 2017 to 3 May 2017 – during the general election that year.
Mr Ball’s lawyers lodged an application in February to summons Mr Johnson, claiming the MP had deliberately misled the public during the first campaign, and repeated the statement during the second.
Lewis Power QC, who represents Mr Ball, said Mr Johnson’s conduct had been “both irresponsible and dishonest”.
But Mr Johnson’s representatives said the case was about “the desire on the part of individuals, such as Mr Ball, to undermine the referendum result”.
In her written ruling, District Judge Margot Coleman said: “I accept that the public offices held by Mr Johnson provide status, but with that status comes influence and authority.
“I am satisfied there is sufficient to establish prima facie evidence of an issue to be determined at trial of this aspect.”
Brexit: Boris Johnson ordered to appear in court over £350m claim}