The Sherman Antitrust Act of 1890 (26 Stat. 209, 15 U.S.C. §§ 17) is a United States antitrust law which prescribes the rule of free competition among those engaged in commerce. It was passed by Congress and is named for Senator John Sherman, its principal author.

The Sherman Act broadly prohibits 1) anticompetitive agreements and 2) unilateral conduct that monopolizes or attempts to monopolize the relevant market. The Act authorizes the Department of Justice to bring suits to enjoin (i.e. prohibit) conduct violating the Act, and additionally authorizes private parties injured by conduct violating the Act to bring suits for treble damages (i.e. three times as much money in damages as the violation cost them). Over time, the federal courts have developed a body of law under the Sherman Act making certain types of anticompetitive conduct per se illegal, and subjecting other types of conduct to case-by-case analysis regarding whether the conduct unreasonably restrains trade.

The law attempts to prevent the artificial raising of prices by restriction of trade or supply. "Innocent monopoly", or monopoly achieved solely by merit, is legal, but acts by a monopolist to artificially preserve that status, or nefarious dealings to create a monopoly, are not. The purpose of the Sherman Act is not to protect competitors from harm from legitimately successful businesses, nor to prevent businesses from gaining honest profits from consumers, but rather to preserve a competitive marketplace to protect consumers from abuses.

The United States Department of Justice (DOJ), also known as the Justice Department, is a federal executive department of the United States government tasked with the enforcement of federal law and administration of justice in the United States. It is equivalent to the justice or interior ministries of other countries. The department is headed by the U.S. Attorney General, who reports directly to the president of the United States and is a member of the president's Cabinet. The current attorney general is Merrick Garland, who was sworn on March 11, 2021.The modern incarnation of the department was formed in 1870 during the Ulysses S. Grant presidency. The department is composed of federal law enforcement agencies, including the U.S. Marshals Service, the Federal Bureau of Investigation, the Bureau of Alcohol, Tobacco, Firearms and Explosives, and the Drug Enforcement Administration and the Federal Bureau of Prisons. The primary actions of the DOJ are investigating instances of white collar crime, representing the U.S. government in legal matters (such as in cases before the Supreme Court), and running the federal prison system. The department is also responsible for reviewing the conduct of local law enforcement as directed by the Violent Crime Control and Law Enforcement Act of 1994.