Last week’s ruling that the FBI raid of Rep. William Jefferson’s (D-La.) Congressional office was unconstitutional might bolster Jefferson’s efforts to challenge some of the evidence the government relied upon to file bribery charges against him, his lawyers said Friday.

But other legal observers said the most dramatic impact may come in future corruption investigations, as the ruling left no clear procedures for how law enforcement agencies can get access to relevant materials in a Congressional office.

The U.S. Court of Appeals for the District of Columbia ruled on Friday that the May 2006 raid of Jefferson’s office in the Rayburn House Office Building violated the Speech or Debate Clause of the Constitution, which protects Members of Congress from prosecution for their legislative activities.

The FBI raided Jefferson’s office and had a “filter team” screen out those documents that seemed to be legislative materials from those that were not. Jefferson argued that he should have had the right to proactively determine which documents were subject to the Speech or Debate protection.

The court ruled that “a search that allows agents of the Executive to review privileged materials without the Member’s consent violates the [Speech or Debate] Clause. The Executive’s search of the congressman’s paper files therefore violated the Clause.”

The ruling orders the Justice Department to return to Jefferson those paper files for which he can claim the Speech or Debate protections. The court did not order the return of electronic files or paper documents that are not privileged.

Justice Department spokesman Brian Roehrkasse said Friday, “The Department of Justice is pleased that the D.C. Circuit opinion does not find that the search of a Congressional office is unconstitutional. We are disappointed with the ruling that requires that a Member of Congress be provided advance notice and the right to review materials before the execution of a search warrant.”

Nevertheless, Roehrkasse said the ruling would not affect prosecution of Jefferson on bribery charges. The Justice Department in June filed an indictment against Jefferson for allegedly accepting bribes and participating in a scheme to bribe officials in Africa on behalf of a telecommunications company that was trying to get contracts there. Jefferson has denied any wrongdoing.

The appeals court ruling was issued two years to the day after the FBI raided Jefferson’s homes in Louisiana and Washington, D.C., finding $90,000 in cash in his freezer.

“Because of the procedures that were put in place for the execution of the search warrant, the indictment and prosecution of Congressman Jefferson will not be negatively impacted by this decision,” Roehrkasse said. “The Department of Justice will continue to prepare for trial, scheduled for January 2008, and we are pleased that the D.C. Circuit opinion allows the prosecutors to retain non-Speech or Debate Clause documents.”

But Jefferson’s lawyer said the ruling may support their challenge of the evidence being used against him.

“We have made the argument that this was an illegal search, so whatever they got was illegally obtained,” regardless of whether it was subject to a privilege, said Robert Trout, Jefferson’s lawyer. Trout said the Congressman’s legal team is preparing to litigate the question of what evidence the government may use against him and will be filing briefs on that issue in September.

The appeals court decision at least supports Jefferson’s argument that the search of his office was improper, Trout said.

Whatever the impact on Jefferson, observers said the ruling may be far more significant for future corruption investigations of other Members of Congress.

“The bottom line is that the Justice Department is going to think long and hard before they do it again, and if they do it again they are going to think long and hard about what procedures they would use,” said James Hamilton, who filed an amicus brief in the case on behalf of former Speakers Newt Gingrich (R-Ga.) and Tom Foley (D-Wash.) and former House Minority Leader Bob Michel (R-Ill.).

Melanie Sloan, executive director of Citizens for Responsibility and Ethics in Washington, said the ruling appears to allow other Members in legal trouble to simply store incriminating documents in their Congressional offices, where they will be beyond the reach of the FBI.

The court ruled that a Congressional office can in fact be searched but said it would be up to the executive and legislative branches to work out procedures for doing so in a way that would protect a Member’s privilege. Several parties to the case offered solutions such as having the Capitol Police seal the office before either the FBI or the Member of Congress could enter.

Reid Stuntz — a lawyer at Hogan & Hartson and a former Congressional staffer who, along with other former staffers, filed a brief arguing the search of Jefferson’s office violated the Speech or Debate Clause — said the court is not declaring that Congressional offices are sanctuaries. The ruling affirms that “if one branch is investigating the other, and they cannot come to an accommodation, you need a third branch [the courts] to resolve that dispute” and to determine the scope of a lawmaker’s privilege, Stuntz said.

But sources said there has been no progress on working out such an arrangement since the president directed the two sides to discuss the matter after the raid on Jefferson’s office last year. If the Justice Department intends to search another Congressional office, there currently are no agreed-upon procedures for how to do it, sources said.