(CNN)Michael Sussmann, the lawyer for the Democrats accused of lying to the FBI in 2016, called Special counsel John Durham's investigation "prosecutorial overreach" in a new court filing on Thursday, seeking to have his charge thrown out.

       Durham has charged Sussmann with lying to then-FBI General Counsel James Baker about representing Hillary Clinton and a tech company. In the meeting with Baker, Sussmann shared suspicious computer data that seemed to suggest Donald Trump and his associates had contact with a Russian bank.

       Unspooling the latest twists in special counsel John Durham's investigation

       Sussmann, formerly a lawyer with the Democratic Party-tied law firm Perkins Coie, has maintained that he didn't lie to Baker about who he represented. Thursday, Sussmann argued that ultimately didn't matter to the FBI's Russia investigation, which at the time was in its infancy.

       "He met with the FBI, in other words, to provide a tip. There is no allegation in the indictment that the tip he provided was false. And there is no allegation that he believed that the tip he provided was false," Sussmann's legal team wrote.

       Durham has been investigating the origins of the FBI's probe into supposed ties between Trump and Russia, which eventually netted several convictions of top Trump advisers. But no one was charged with a conspiracy with Russia, and when the FBI investigated suspicions of a Trump Organization-Russia connection, it found "insufficient evidence" of a secret communications channel, prosecutors said.

       Read More

       Earlier this week, Sussmann pushed back against Durham after the special counsel insinuated that he and the tech company he represented also misled the CIA about the use of Russian phones around Trump , in a vague court filing last Friday. Sussmann and the tech executive he worked with, Rodney Joffe, say they did not aim to manipulate federal officials out of political animus, and that Durham's suggestions, which quickly took off in right-wing media, were wrong.

       Sussmann is scheduled to have a trial in May. But first, the federal judge overseeing the case, Christopher "Casey" Cooper of the DC District Court, must decide whether the prosecutors' case is legally sound enough to move forward. The filing on Thursday is the first step in that process.

       Sussmann's team says Durham's approach to the case could harm free speech, "dissuade honest citizens from coming forward with tips, and chill the advocacy of lawyers who interact with the government," according to the filing.