Optimal Leniency Programs When Firms Have Cumulative and Asymmetric Evidence

An antitrust authority deters collusion with the use of fines and a leniency program. Firms have imperfect cumulative evidence of the collusion. That is, cartel conviction is not automatic if one firm reports. Reporting makes conviction only more likely: the more that firms report, the more likely is conviction. Furthermore, the evidence is distributed asymmetrically among firms. This set-up allows us meaningfully to analyze three typical features of leniency programs: minimum-evidence standards; ringleader discrimination; and marker systems. Minimum-evidence standards provide high-evidence firms with proper incentives to report. They are better at deterring than is ringleader discrimination. Under a marker system only one firm reports so that the antitrust authority never gets the entire available evidence. Appropriate minimum-evidence standards make a marker system redundant.