In the case of Reeves, Inc. v. Stake et al., 1979, the U.S Supreme Court ruled in favor of South Dakota's state-owned cement plant which had prioritized selling to in-state customers during a period of shortage over out-of-state buyers like Reeves, Inc. The court held that there was no violation of the Commerce Clause by preferring local consumers over non-residents during times when demand exceeded supply. This decision was based on two main reasons: first, it recognized states as market participants rather than regulators; secondly, it acknowledged that any burdens imposed on interstate commerce were incidental and not protectionist in nature since they did not stimulate or favor local economic activity at the expense of out-of-state businesses.

In the dissenting opinion for Reeves, Inc. v. Stake et al., Justice Powell argued that South Dakota's decision to stop selling cement from its state-owned plant to out-of-state customers was a violation of the Commerce Clause of the U.S. Constitution, which prohibits states from discriminating against interstate commerce. He contended that this case represented an unprecedented expansion of state immunity under the market participant doctrine and warned about potential negative consequences on national unity and economic integration if states were allowed to favor their own citizens in such a manner without any substantial justification or scrutiny by courts. He also disagreed with majority’s view that there is no significant difference between a private business and a state acting as market participants; he believed it would lead to erosion of constitutional protections against discriminatory practices by states.