In the case of Chicago & Alton Railroad Company v. Wagner, 1915, the U.S Supreme Court ruled in favor of Wagner, an employee who was injured while working for the railroad company. The court held that under the Federal Employers' Liability Act (FELA), a federal law enacted to protect and compensate railroad workers injured on the job, Wagner was entitled to damages from his employer due to their negligence which led to his injury. The ruling clarified that FELA does not require employees to prove absolute negligence on part of their employers; rather it is enough if they can demonstrate that employer's negligence played any part in causing injuries even if worker's own negligence also contributed towards it. This decision set a precedent for future cases involving workplace injuries within industries governed by similar laws.

In the dissenting opinion for Chicago & Alton Railroad Company v. Wagner, it was argued that the majority's decision to hold the railroad company liable for damages suffered by an employee due to negligence of a fellow servant contradicted established legal principles. The dissent emphasized that under common law, employers were not responsible for injuries caused by co-workers unless they had been negligent in hiring or supervising them. They contended that this principle should apply even when safety statutes are in place unless those laws explicitly state otherwise. In this case, there was no evidence presented showing negligence on part of the employer regarding hiring or supervision practices which could have led to injury; therefore, according to their interpretation of both statutory and common law rules governing employer liability, they believed holding the railroad company accountable was unjustified.