Jefferson, D-La., says the Justice Department crossed the line when it raided his office in a bribery investigation. His lawyer argued that point before a three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit.
His attorney said nearly 19,000 pages of documents and electronic files seized by prosecutors and the FBI are covered by the constitutional principle that the executive branch may not use its law enforcement powers to infringe on the independence of the legislative branch.
Attorney Robert P. Trout told the court that the search was unconstitutional because, while FBI agents looked for documents related to their criminal investigation, they also examined many other records related to Jefferson's work as a legislator.
"How do we know an FBI agent — there were 15 FBI agents over 18 hours — didn't say, 'Hey Joe, get a load of this. This is really interesting,"' Trout said.
Trout said Jefferson or an attorney for the House should have been allowed to review the documents first to decide what should not be provided to the FBI.
Judge Judith W. Rogers questioned whether the Justice Department carried out the raid appropriately.
"The question in my mind is the manner in which it was done," she said.
Deputy Solicitor General Michael Dreeben said Jefferson sought "a key to the evidence locker" and said such a policy "in effect destroys the governments ability to execute a search warrant."
The raid was part of a 16-month international investigation of Jefferson, who allegedly accepted $100,000 from a telecommunications businessman, $90,000 of which was later recovered from a freezer in the congressman's Louisiana home.
If FBI agents were forced to work through attorneys to get crucial evidence, Dreeben said, the result would be "massive delay and obstruction of the investigation."
The bulk of the Jefferson investigation has essentially been on hold since last summer because of the legal fight.
Jefferson, who won re-election last year despite the looming investigation, did not attend the court hearing.
The case has cut across party lines and made for some strange alliances. Former House Speakers Newt Gingrich, a Republican, and Thomas Foley, a Democrat, have filed legal briefs opposing the FBI raid, along with former House Minority Leader Robert Michel, a Republican.
Liberal watchdog group Citizens for Responsibility and Ethics in Washington joined conservative groups Judicial Watch and the Washington Legal Foundation in supporting the legality of the raid.
The case is being considered by Chief Judge Douglas H. Ginsburg, Judge Karen Lecraft Henderson and Rogers.
Ginsburg and Rogers served in the Justice Department and Henderson served as deputy South Carolina attorney general. None of the judges served in the legislative branch, though Rogers was counsel to a congressional commission formed to review Washington's municipal structure. Ginsburg and Henderson were appointed by Republican presidents, Rogers by a Democrat.