Munn v. Illinois, case decided by the U.S. Supreme Court in 1876. Munn, a partner in a Chicago warehouse firm, had been found guilty by an Illinois court of violating the state laws providing for the fixing of maximum charges for storage of grain (see Granger movement). He appealed, contending that the fixing of maximum rates constituted a taking of property without due process of law. The Supreme Court upheld the Granger laws, establishing as constitutional the principle of public regulation of private businesses involved in serving the public interest.