39 U.S.C. § 604 — Seizing and detaining letters

A Postal Service officer or employee whose duties involve inspecting postal matters, a customs officer, or a United States marshal or deputy marshal may seize at any time letters and bags, packets, or parcels containing letters that are being carried illegally on a vessel or post road. The officer or employee who makes the seizure must take the seized items to the nearest post office. On the direction of the Postal Service or the Secretary of the Treasury, that officer or employee may instead hold the items until two months after all lawsuits and other proceedings have been finally decided. Those lawsuits or proceedings must be brought against a person for sending or carrying the letters within six months after the seizure.