The United States Supreme Court has held that a home rule municipality is not exempt from liability under the Sherman Antitrust Act unless the municipality's action constitutes an action of the state itself or is municipal action in furtherance or implementation of a clearly articulated and affirmatively expressed state policy to displace competition.
Community Communications Co. v. City of Boulder, 102 S. Ct. 835 (1982).
June F. Swanson,
Antitrust Law - Sherman Act - Home Rule Municipalities - Municipal Ordinances,
Duq. L. Rev.
Available at: https://dsc.duq.edu/dlr/vol21/iss3/7