The Federal Interstate Commerce clause often grants the Feds criminal jurisdiction. That clause gives the Feds sole power to govern interstate business issues such as telephone, television, trucking, U.S. Mail, and air travel, to name a few. It’s the reason that sex with a minor becomes a Federal crime if she is taken over a state line. Other areas of criminal law that will invoke Federal jurisdiction are national security, the military, the Post Office, Federal Taxes, and Federal benefit entitlement programs. Graffiti is a local crime, but not if it’s on a Post Office building. Similarly, tax evasion or tax fraud, evading the military draft, breaking into a National Guard armory, or Welfare Fraud can all wind you up in Federal Court.

What about this? Joe gets drunk in San Francisco, drives to Las Vegas, stops to make an obscene gesture to a Federal Senator, and then he is arrested, still under the influence. Who gets Joe, the Feds or Las Vegas Police? Answer: the locals. His driving across the state line drunk has no national significance to the Feds. He did not threaten the Senator, and has a right to free speech, so his only offense is local drunk driving.

Note: many criminal cases are mixed. The Feds can allow the state to prosecute a small bank robbery. A Federal Prosecutor with a racketeering case can also prosecute a violation of a state murder law involved in their case.