Antitrust laws are regulations that encourage competition by limiting the market power of any particular firm; these laws can prevent multiple firms from colluding or limit competition through practices such as price fixing. In the 1922 case of Federal Baseball Club of Baltimore v. National League, the U.S. Supreme Court ruled that baseball was not considered interstate commerce, and therefore, antitrust laws did not apply to the business of baseball. The decision was based on the idea that baseball was a local activity and not subject to federal regulation under the Commerce Clause of the U.S. Constitution. Subsequent decisions and legislative actions have extended certain exemptions to other professional sports leagues. For example, the Sports Broadcasting Act of 1961 provides a limited antitrust exemption for the joint selling of television broadcast rights by professional football, baseball, basketball, and hockey leagues.