The article first outlines the four elements of a criminal antitrust violation under Section 1 of the Act. A civil plaintiff must establish three elements to prove a violation of Section 1: an agreement to concerted action, such as a combination or conspiracy formed by two or more entities; that the agreement unreasonably restrained trade or commerce; and that the restrained trade or commerce was interstate or international in nature. In a criminal antitrust prosecution, the government must prove an additional fourth element, i.e., that the defendant intended to restrain commerce. The article next presents the defenses to an allegation of an antitrust violation. Three of the defenses are withdrawal from a conspiracy, statute of limitations, and double jeopardy. These defenses focus on the length and scope of the charged conspiracy. Three other defenses focus on the importance of the identities of the concerned actors and relevant markets. They address the single entity, respondent superior, and meeting competition defenses. Another four defenses present the argument that a “conflict between different bodies of law will require that the antitrust laws be displaced.” These defenses pertain to state action immunity, petitioning government, regulated industry, and foreign commerce. Following the presentation of defenses, the article distinguishes between Federal, State, and international antitrust enforcement. The concluding section of the article explains the penalties for criminal antitrust violations. It identifies the factors considered by courts in setting penalties for corporations and individual defendants, and it discusses the trend in increasing fines for antitrust violations. 253 notes