The U.S. Department of Justice aggressively prosecutes shipowners and operators of foreign-flag vessels calling at U.S. ports for MARPOL violations. These prosecutions are often the result of an initial inspection and investigation by the U.S. Coast Guard. Our authors both served as US Coast Guard attorneys before moving to the private sector. They share their insights into the rights and responsibilities of shipowners and crew when interacting with U.S. Coast Guard inspectors and investigators.