Section 89 of Title 14 of the United States Code "authorizes the Coast Guard to board vessels subject to the jurisdiction of the U.S., anytime upon the high seas and upon waters over which the United States has jurisdiction, to make inquiries, examinations, inspections, searches, seizures and arrests."
A vessel underway, when hailed by a Coast Guard vessel is required to "heave to", or stop, and maneuver in such a manner that permits a Coast Guard boarding officer to come aboard. Other federal, state and local law enforcement officials may board and examine your vessel, whether it is numbered, unnumbered or documented.
Sometimes various government agencies interested in guarding or protecting U.S. waterways may join forces with other local, state or federal agencies. When these agencies form a task force, Coast Guard law enforcement personnel may be found aboard the vessels of other U.S. agencies, but they still retain the authority given to them under Section 89 of Title 14 of the United States Code.
