By: Christopher R. Leslie (CLS Blue Sky Blog)
Antitrust plaintiffs typically rely on circumstantial evidence when pursuing price-fixing claims, because price-fixing conspirators usually conceal their collusion through code names, secret meetings, cover stories, and falsified documents. Antitrust law uses a two-step process for proving price-fixing agreements through circumstantial evidence. First, the plaintiff shows that the defendants engaged in similar conduct, referred to as “conscious parallelism.” Second, the plaintiff presents plus factors, which are evidence that suggests the defendants’ parallel conduct is the product of collusion, not independent decisions by the defendant firms. Following the Supreme Court’s mandate in Continental Ore Co. v. Union Carbide & Carbon Corp. that judges and juries should not compartmentalize an antitrust plaintiff’s proffer of proof,[1] lower courts recognize that they should not isolate the plus factors presented by a plaintiff.
Courts have not developed a comprehensive list of plus factors. Collectively, however, antitrust opinions have recognized well over 20 individual plus factors. But no antitrust opinion explains why each particular plus factor is evidence of illegal collusion or discusses the relationships among plus factors.
Categorizing plus factors can help judges understand how each plus factor plays an important role in a circumstantial case for proving illegal price fixing. In my article, The Probative Synergy of Plus Factors in Price-Fixing Litigation,[2] I create a typology for antitrust plus factors. Some – such as market concentration, barriers to entry, inelastic demand, an absence of substitutes, and product homogeneity – should be treated as demonstrating Cartel Susceptibility because markets with these characteristics facilitate cartel activity. Another category of plus factors, those related to Cartel Formation, includes proof of a defendant inviting its rivals to collude, a motive to collude, an opportunity to conspire, and intercompetitor communications…
