Mitchel v. Reynolds is a landmark decision in the history of the law of restraint of trade. It is generally cited for establishing the principle that reasonable restraints of trade, unlike unreasonable restraints of trade, are permissible and therefore enforceable and not a basis for civil or criminal liability. It is largely the basis in US antitrust law for the "
rule of reason." William Howard Taft, then Chief Judge of the Sixth Circuit Court of Appeals, later US President and then Chief Justice of the Supreme Court, quoted
Mitchel extensively when he first developed the antitrust rule-of-reason doctrine in
United States v. Addyston Pipe & Steel Co., which was affirmed in 1899 by the Supreme Court. The doctrine also played a major role in the 1911 Supreme Court case
Standard Oil Company of New Jersey v. United States 221 U.S. 1 (1911).