Lawyers for former FBI Director James Comey have asked a federal court to dismiss the criminal case accusing him of threatening US President Donald Trump, alleging prosecutors misled judges, withheld key evidence and submitted false statements during the investigation.
The filings argue that the prosecution is politically motivated and reflects selective enforcement driven by longstanding hostility between Trump and Comey.
Comey was charged in April over an Instagram post showing seashells arranged to form the numbers "86 47", which the Justice Department alleges referenced killing Trump, the 47th US president.
Comey has denied the post carried any violent meaning.
Defence lawyers contend investigators repeatedly failed to establish any link between Comey and the alleged violent meaning of the term "86" but omitted those findings from applications for search warrants.
According to the filings, FBI searches of internal investigative databases and a review of material from a case involving reputed mobster John Gambino uncovered no evidence connecting Comey to the phrase.
The defence also said investigators interviewed government cooperator Salvatore Gravano, who stated he did not recall discussing the term with Comey or hearing it used in connection with the earlier prosecution.
Lawyers further allege that warrant applications contained false statements and omitted information, including the initial interpretation of a witness who first understood "86" as a restaurant term before later associating it with violence after hearing comments by Rudy Giuliani.
The filings state the FBI determined Giuliani's claims about Comey's knowledge of the expression were untrue.
Comey's legal team also argues the prosecution forms part of a broader campaign of political retaliation against one of Trump's longstanding critics.
The filings seek access to grand jury transcripts, allege unlawful Secret Service surveillance and claim Trump received regular updates during the investigation.
"Ample objective evidence — much of which comes directly from government officials’ own public statements and admissions — establishes that the President’s animus toward Mr Comey led to this vindictive and selective prosecution," the defence wrote.
The Justice Department has not yet responded to the latest filings.
Acting Attorney General Todd Blanche previously said prosecutors intended to prove criminal intent through witnesses, documents and other evidence presented in court.