In Cantor v. Detroit Edison, the U.S. Supreme Court held that a power utility regulated by the State of Michigan is not immune from federal antitrust liability, even though the Michigan Public Service Commission had approved the utility's activity under attack-a light-bulb program for customers-and the utility by state law had to maintain the program until it filed a new tariff with the Commission.
Pierce, Richard W.
"Antitrust and State Action: Lights Out for a Regulated Utility,"
Mercer Law Review: Vol. 28:
3, Article 9.
Available at: https://digitalcommons.law.mercer.edu/jour_mlr/vol28/iss3/9