The challengers, including Exxon, claimed that the law violated the Dormant Commerce Clause. Justice Stevens wrote for the majority, which disagreed with Exxon et al.: "Since Maryland's entire gasoline supply flows in interstate commerce and since there are no local producers or refiners, such claims of disparate treatment between interstate and local commerce would be meritless."
Majority held that Act does not (1) discriminate against interstate dealers (2) does not prohibit the flow of interstate goods (3) place added cost on them (4) or distinguish between in-state or out-of-state retailers. The absence of any of these factors fully distinguishes this case from Hunt v. Washington Apple Commission.
The Court held that the regulation was constitutional despite huge extraterritorial effects of the regulation, less burdensome options available to the state, and no legitimate state interest apart from a desire for cheaper oil. This case is an exception to the rules set forth in Pike v. Bruce Church.