What is the US's largest regulatory agency?

Answer 1

My guess is the U.S. postal system based on pure employees. Yes, you can be arrested by the post office (although not by the common carrier). Mail fraud, wire fraud, mail theft, destruction of mail, the destruction of private and public mail boxes ect. are handled by the post office. The EPA would be second and almost all of its employees can file criminal charges and is a pure regulatory agency where the U.S's secondary duty is to uphold the law.