While there are a few exceptions, international waters are generally 24 miles from a country’s shoreline. Usually, inside this boundary, the laws of the country are still in effect; however, once more than 24 miles from the coast, the boat is under the jurisdiction of its homeport.
Within this 24-mile area, the coastal country patrols the waters. For instance, in the United States, the U.S. Coast Guard polices the seas from the coast to 24 miles out to sea. If the Coast Guard feels that a ship travelling through these waters is carrying drugs or other contraband, they are within their rights to board and search the ship.