A trial over whether a lawyer with ties to the Democratic Party lied to the FBI in 2016 is set to begin on Monday in what could be the first major test for John Durham, the special counsel appointed during the Trump administration to investigate the former president’s allegations of a conspiracy to undermine his campaign. 

Michael Sussmann, a former partner at the law firm Perkins Coie, is charged with making false statements to the FBI’s top lawyer during the 2016 campaign when he handed over data to the bureau purporting to show links between Trump and a Russian bank.

Durham’s office is alleging that Sussmann, who was representing Hillary Clinton’s campaign and a cybersecurity researcher at the time, falsely claimed he was not representing any particular client when he met with then-FBI general counsel James Baker in September 2016.

The FBI looked into Sussmann’s evidence — internet data purporting to show a line of communication between the Trump Organization and the Russian Alfa Bank — and found nothing to support the allegations.

The trial will center on the question of whether Sussmann lied when he said his clients did not prompt the tip to the FBI, and if he did, whether that lie was material in that it affected how federal law enforcement pursued the investigation.