This essay presents a systematic study of the incidence of universal jurisdiction (UJ) prosecutions for the international crime of piracy. Using data on the number of piracies committed in a twelve-year period (1998-2009) obtained from international agencies and maritime industry groups, we determined the percentage of these cases where nations exercised universal jurisdiction. Studies of the worldwide use of UJ prosecutions for other crimes simply count how often universal jurisdiction has been exercised but do not attempt to determine the rate of prosecution. Simply counting cases does not allow one to appreciate the significance of universal jurisdiction in relation to the total problem. While the expressive or symbolic value of universal justice may be satisfied by a small number of isolated prosecutions, the deterrent effect depends on its incidence relative to the number of perpetrated crimes.