Great question. Honestly, in high school if they offer any criminal justice or law classes they might help you along. I agree with both Jeffrey and Jill. I know in NYC to become a police officer they require an associates degree (no specific major) and passing the police exam. Each State has different requirements and depending on whether or not you go federal, like the CIA, or State and local like a police officer there will be differences. Start by looking up job requirements for each and move on from there.