The US Supreme Court upheld a ruling that barred FBI agents from searching the legislative office of congressman William Jefferson as part of a corruption investigation.

It was the second time in a week that the judges have rebuffed President George W. Bush’s expansive view of the powers of the government’s executive branch. The ruling could also damage a separate corruption case brought by prosecutors against Rick Renzi, an Arizona congressman, and limit the tactics investigators use to probe lawmakers in the future.