The U.S. Supreme Court case Denver & Rio Grande Western Railroad Co. v. Union Pacific Railroad Co., et al., in 1955 revolved around a dispute between two railroad companies over the right to use certain tracks in Salt Lake City, Utah. The Denver & Rio Grande Western Railroad Company (D&RGW) had been using the disputed tracks under an agreement with Oregon Short Line and Utah Northern Railway Company, which was later acquired by Union Pacific Railroad Company (UP). However, UP sought to terminate this arrangement and take exclusive control of the track usage rights. D&RGW sued UP for breach of contract and won at both district court level and on appeal before it reached the Supreme Court. In its decision, the Supreme Court ruled that while there were ambiguities in how long D&RGW's right to use these tracks would last under their original agreement with Oregon Short Line, those ambiguities should be resolved against UP as they drafted the contract language being disputed. Therefore, D&RGW retained its rights to continue using these railway lines.

The dissenting opinion in the case of Denver & Rio Grande Western Railroad Co. v. Union Pacific Railroad Co., et al., argued that the majority's decision to uphold a lower court ruling, which allowed Union Pacific to acquire control over Western Pacific without approval from the Interstate Commerce Commission (ICC), was incorrect and potentially harmful for competition within the railroad industry. The dissent believed that this acquisition should have been subject to ICC review under Section 5(2) of the Interstate Commerce Act, as it involved significant changes in corporate control and could impact public interest by reducing competition among railroads serving western states. They also disagreed with majority’s interpretation of “control” arguing that even minority stock ownership can result in de facto control due to various factors such as voting agreements or disproportionate influence on board decisions.