Almost no one beats federal charges, because if the they're coming after you they'll have an airtight case before you ever go to trial. They'll put the screws to everyone you know, your bank, your dog, your coffee shop to get the evidence they need. If they think there's even a chance you'll beat the charge, they just don't bring the case.

[EDIT] If you disagree, I'd suggest you read a bit that Ken White has written about federal prosecutions. Basically if they really want you, they'll trip you up in interviews and charge you with lying to the FBI.