This essay surveys longitudinal data on private antitrust enforcement collected by the Administrative Offices of the U.S. Courts. These data suggest that the incidence of private antitrust enforcement in the United States has been relatively stable since the mid-1980s, with aggregate annual new filings typically in the range of 600-900. Resolution by trial remains a rare last resort, averaging often less than 1 percent a year. Approximately a quarter of cases settle and the other three-quarters are involuntarily dismissed at the motion to dismiss or summary judgment stage — a ratio that has not been strongly affected over recent decades by case law developments or other factors.
