In the case of Cities Service Oil Co. v. Dunlap et al., 1939, the U.S Supreme Court ruled in favor of Cities Service Oil Company (now CITGO). The dispute arose when a group of landowners in Oklahoma claimed that they were entitled to royalties from oil and gas wells on their property under an agreement made with Cities Service Oil Co. However, the company argued that it had fulfilled its obligations by drilling one well on each tract of land as per their contract's terms. The court agreed with this interpretation and held that the obligation was satisfied once a single well was drilled per tract regardless if there were multiple owners for each piece of land or not.

In the dissenting opinion for Cities Service Oil Co. v. Dunlap et al., it was argued that the majority's decision to uphold a state law requiring oil companies to sell gasoline at uniform prices across all regions of Oklahoma, regardless of transportation costs, violated principles of interstate commerce and equal protection under the Fourteenth Amendment. The dissent contended that this law unfairly burdened out-of-state businesses by forcing them to absorb additional distribution costs not experienced by local competitors, thereby creating an unfair advantage in favor of intrastate commerce over interstate commerce. Furthermore, they believed this regulation infringed upon economic liberties protected under the Constitution by dictating how private entities should price their goods or services without sufficient justification from public interest considerations.