Sam Kleiner notes that environmental activists are more likely now than ever to face piracy charges for their high-seas hijinks:
Traditionally, piracy was carried out as a form of robbery to enrich the pirates. In the ‘golden age’ of piracy, pirates such as Blackbeard commanded large fleets of ships and amassed huge fortunes on the high seas. The pirate crews also profited from the raids and there were even systems of workman’s compensation for the crews.
Under international law, piracy prosecutions traditionally required that the alleged pirates were seeking private gains. The Harvard Draft Convention on Piracy from 1932 noted that, “If an attack by a ship manned by insurgents is inspired by a motive of private plunder, it may be piracy under the definitions of the draft convention.” Under the United Nations Convention on the Law of the Sea, piracy requires the use of violence against a ship when it is “committed for private ends.” The requirement fits with the traditional definition of a pirate as a businessman seeking to enrich himself and his crew. In the 1820 case of United States v. Smith, the U.S. Supreme Court defined piracy as “robbery on the high seas.”
But now that’s changing: Nations have begun to accept the idea that piracy can include politically motivated attacks on ships, even by environmentalists.