The United States Supreme Court, distinguishing between sales and agency transactions, has held that vertical territorial or customer restrictions of a manufacturer relative to a sale are per se violations and that restrictions incidental to an agency relation are subject to the rule of reason.
United States v. Arnold, Schwinn & Co., 388 U.S. 365, 87 S. Ct. 1856 (1967).
Dennis P. Mankin,
Antitrust - Vertical Restraints of Territory and Customers - Section 1 of the Sherman Act,
Duq. L. Rev.
Available at: https://dsc.duq.edu/dlr/vol6/iss2/9