Ethics lawyers are dealing with plenty of anxious clients; no one wants to be a test case for a federal prosecutor. But in a town where many lobbyists, lawmakers, and congressional aides are neighbors and friends, lobbyists worry that they could accidentally violate the rules, says Cindi Berry, chairwoman of the advocacy and government relations practice group at Powell Goldstein.

"I'm constantly fielding calls from clients who are fixated on hypothetical scenarios like, 'If I have a block party and someone who happens to be a staff member who I didn't invite comes with another friend, and I see they are eating a shrimp at my house, do I have to tell them to take the shrimp out of their mouth?' " That would be a technical violation of the law, Berry says, and "everyone is worried some overzealous prosecutor will go after someone who didn't intend to do anything wrong."