This is a survey of the economic principles that underlie antitrust law and how those principles relate to competition … policy. We address four core subject areas: market power, collusion, mergers between competitors, and monopolization. In each … central features of antitrust policy. Our objective is to foster the improvement of legal regimes and also to identify topics …

We augment the multi-market collusion model of Bernheim and Whinston (1990) by allowing for firm entry into, and exit … from, individual markets. We show that this gives rise to a new mechanism by which a cartel can sustain a collusive … agreement: Collusion at the extensive margin whereby firms collude by avoiding entry into each other's markets or territories …

; this is equivalent to modeling firms as an implicit cartel playing a punishment game. We show that coordination can … partially or fully eliminate the first kind of inefficiency, depending on the magnitude of the punishment, but cannot always … remove the second. The response of prices to a monetary shock will depend on the magnitude of the punishment, and may be …

collusion and greater market share for domestic firms during periods of low demand as a result. This occurs in spite of the fact …

Though economists have made substantial progress toward formulating theories of collusion in industrial cartels that … observation that cartels keep participants in line through the threat of punishment, but they fail to explain two important … it is detected. We propose a theory of "equilibrium price cutting and business stealing" in cartels to bridge this gap …

We present a simple model of the effects of hate crime legislation. It shows that even if the direct harm to victims of … hate crime is the same as for other crimes, because of other differences in the effects it may still be optimal to exert … more law-enforcement effort to deter or prevent hate crime. These differences also have previously unrecognized effects on …

A number of recent antitrust lawsuits have been settled with discount contracts in which the defendants agree in the …

(used by Facebook). We find that, despite its well-known susceptibility to collusion, the VCG mechanism outperforms the GSP …