United States Postal Inspection Service

The United States Postal Inspection Service (USPIS) is the federal law enforcement arm of the United States Postal Service. It supports and protects the United States Postal Service, its employees, infrastructure, and customers by enforcing the laws that defend the United States' mail system from illegal or dangerous use. Its jurisdiction covers any crimes that may adversely affect or fraudulently use the United States Mail, the postal system, or postal employees. With roots going back to the late 18th century, the USPIS is the country's oldest continuously operating federal law enforcement agency.

There are approximately 200 federal crimes that can be committed which involve the mail. Therefore, the U.S. Postal Inspection Service's activities are broad and ever-changing. In 2024, postal inspectors made 4,440 arrests leading to more than 4,000 convictions, mostly involving mail theft, mail fraud, and prohibited mailings. The growth in illegal narcotics has resulted in more than 20,000 arrests and the seizure of over $30 million in drug proceeds since 2010. In 2024, postal inspectors made 2,034 arrests involving drug trafficking, seized more than 36,000 kilograms of illegal drugs from the mail, and confiscated more than $13.8 million in illicit proceeds. In some cases, these seizures were performed with the assistance of a detection dog.

As of 2024, there were over 1,200 postal inspectors, who are authorized to carry weapons, make arrests, execute federal search warrants, and serve subpoenas.