Munn v. Illinois was one of the Granger cases, and involved the validity of an 1871 Illinois law.
During the height of the 1870s depression, the Illinois legislature responded to the pleas of embattled farmers by enacting a law that established a maximum charge that could be imposed by grain storage facility operators. A Chicago warehouse firm known as Munn and Scott was found guilty in 1872 of violating the law. The Munn and Scott appealed the matter to the Illinois supreme court, which affirmed the ruling of the lower court, and then federal courts up to the United States Supreme Court in 1876, which rendered a decision by a 7-2 vote in March 1877.
The majority upheld the Illinois law and reasoned that a state has a legitimate police power to regulate private enterprises that may adversely impact the public interest. The Court refused to accept the operators` arguments that the due process clause had been violated or that a state role in commerce regulation clashed with the Congressional role. Instead they stated that a state might act, "even though in so doing it may indirectly operate upon commerce outside its jurisdiction."
Munn v. Illinois introduced a short era in which U.S. public utilities were subjected to increased scrutiny. The Court later upheld state efforts to regulate railroad rates. Critics bemoaned the growth of socialism in the country, fearing that private enterprise was being hobbled.
The Court would abruptly reverse direction in the Wabash case of 1886. And so forth.