Introduction: Piracy and occasional state power

States exert their power over maritime predation only occasionally depending on prevalent circumstances. Historically, when states have perceived and attempted to address a problem of piracy, they have encountered severe limits on their abilities to manage private maritime enterprise in waters under their purported control. Despite the popular conception that piracy falls into the legal category of 'universal jurisdiction', such jurisdiction has only been employed sporadically. In reality, despite high-profile 'terror' campaigns against pirates, states regularly employed alternative means of suppression, including negotiation, legal posturing and co-optation. The four articles in this Forum provide detailed case studies of the occasional use of state power to regulate maritime predation in diverse waters and contexts. In these examples, states respectively negotiated with maritime communities in medieval England, sought a monopoly on violence in the South China Sea, collaborated with other states to police colonial Hong Kong, and dealt diplomatically with a local pirate hero to defend New Orleans. Across each article, the 'state' faced a particular problem of piracy, but could only occasionally exert power to manage it.