

Countries may allow for extraterritorial jurisdiction in competition cases based on so-called "effects doctrine". National competition law usually does not cover activity beyond territorial borders unless it has significant effects at nation-state level. Modern competition law has historically evolved on a national level to promote and maintain fair competition in markets principally within the territorial boundaries of nation-states. National and regional competition authorities across the world have formed international support and enforcement networks. The two largest and most influential systems of competition regulation are United States antitrust law and European Union competition law. Since the 20th century, competition law has become global. The business practices of market traders, guilds and governments have always been subject to scrutiny, and sometimes severe sanctions.

The history of competition law reaches back to the Roman Empire. It is also known as antitrust law (or just antitrust ), anti-monopoly law, and trade practices law the act of pushing for antitrust measures or attacking monopolistic companies (known as trusts) is commonly known as trust busting. Competition law is implemented through public and private enforcement. Competition law is the field of law that promotes or seeks to maintain market competition by regulating anti-competitive conduct by companies.
