The federal antitrust laws, embodied in the Sherman and Clayton acts, are intended to protect competition that affects interstate commerce. These laws apply to all medical practice activities because of the court’s broad definition of interstate commerce. Antitrust laws have three attractions to physicians attacking peer review proceedings. As federal laws, they obviate state law peer review protections. In other business contexts, they are used to attack exclusionary agreements that have a surface resemblance to medical staff contracts. Finally, prevailing plaintiffs can recover three times the proved damages plus their attorney’s fees.

The antitrust laws do not condemn bigness in itself, but they prevent a business from using its size or control of the market (monopoly power) against its competitors. The antitrust laws also prevent competitors from reaching agreements to divide markets (horizontal restraints) or otherwise reduce competition. The policy of the antitrust laws is to protect competition, not competitors. There are certain actions, such as price fixing, that are illegal without reference to their effect on the market. These are called per se violations; they are illegal irrespective of the market power of the offenders. For all other violations, the plaintiff must prove that the business, or businesses, involved in the alleged violation have a dominant market position.