Collusion is an agreement between two or more parties in an effort to fraud or deceive. Collusion is often practiced to coordinate efforts among firms, effectively lessening the degree of competition among them. As a result, collusion can be found in many areas of commerce. An interlocking directorate, where a director sits on the boards of competing corporations, is an example of collusion. Because interlocking directorates facilitate the flow of information between competing firms, this exchange of knowledge reduces the competition between the two firms. The result is that the relationship between the two firms becomes more cooperative and coordinated and less competitive. Because interlocking directorates lead to more concentrated (more monopolistic or less competitive) market conditions, they have been made illegal (Clayton Act, 1914). Collusion occurs most often in oligopolistic market structures, where markets or industries are made up of only a few firms. The output of these markets is concentrated in only a few firms, making the actions of each firm much more significant than if these markets were competitive, that is, comprised of many firms. Oligopoly, the presence of only a few firms in an industry, provides an optimal climate for collusion; it is much easier to monitor the actions of a few competitors than it is to keep an eye on many firms. Overt and covert agreements are common in oligopolies. They take the form of social gatherings among the industry leaders, trade association conventions, and lists of representative prices. The goal of each of these practices is to facilitate the exchange of information among the competing firms in the industry. Price leadership is also common, either in the form of the dominant firm being the price leader or the more subtle form of collusive price leadership. As stated by economist F. M. Scherer, “industry members must recognize that their common interest in cooperative pricing behavior overrides any centrifugal aspirations toward independent behavior.” The most overt form of collusion is the cartel. A cartel is formed when a group of previously competing firms or countries organizes to set prices and control aggregate output from its members. Rather than competing against each other, the members now cooperate and their actions are coordinated. The United States’ motto is “E pluribus unum,” translated “from many, one.” It portrays one nation formed from many states. The same idea applies to a cartel. Where there once were many competitors, now there is the cartel of once-competing members. OPEC, the Organization of Petroleum Exporting Countries, and De Beers, the diamond cartel, are examples of successful cartels. In general, because collusion leads to more market concentration rather than market competition, most forms of collusion have been made illegal in the U.S. The Sherman Antitrust Act (1890) and the Clayton Act (1914), and a few other acts outlaw various forms of cooperation and collusion. These acts attempt to discourage anti-competitive practices improve and, thus, market performance.