37.8 Tying Arrangement. John Sheridan owned and operated a Marathon gas station franchise (see Chapter 29). He sued the franchisor, Marathon Petroleum Company, under Section 1 of the Sherman Act and Section 3 of the Clayton Act charging the company with illegally tying the processing of credit-card sales to the gas station. As a condition of obtaining a Marathon dealership, franchisees-owners had to agree to let the franchisor process credit cards. They could not shop around to see if credit-card processing could be obtained at a lower price from another source. The district court dismissed the case for failure to state a claim. Sheridan appealed. Is there a tying arrangement? If so, how would it violate the law? [Sheridan v. Marathon Petroleum Co., 530 F.3d 590 (7th Cir. 2008)]