Those who violate the Sherman Act are subject to fines and to treble damage actions under §4 of the Clayton Act. The economic rationale for those sanctions is deterrence rather than retribution. In the context of collusion in the nurse labor market, this paper recognizes that the optimal rate of antitrust violations is not zero due to enforcement costs. The paper also examines the policy variables available for deterrence. These include resources allocated to detecting and prosecuting antitrust violations, the fines imposed by the courts, and the multiplier for private damages. The paper mentions, but does not develop in depth, the political difficulties with efforts to increase deterrence.