The twelve-person rule in international maritime law refers to strict safety and regulatory thresholds governing commercial passenger vessels and private yachts. Under international conventions such as the Safety of Life at Sea (SOLAS), any vessel carrying more than twelve passengers is legally classified as a passenger ship, triggering vastly more stringent structural safety mandates, fire suppression systems, life-raft capacities, and certified crew qualifications compared to private yachts carrying twelve or fewer guests.