Sullivan v. Portland and Kennebec Railroad Company is a United States Supreme Court case that was decided in 1877. The case involved a dispute between the plaintiff, Sullivan, and the defendant, the Portland and Kennebec Railroad Company. Sullivan had been employed by the railroad company as a brakeman and was injured while on the job. He sued the company for damages, claiming that the company had been negligent in providing a safe working environment. The Supreme Court held that the railroad company was liable for Sullivan's injuries. The Court found that the company had a duty to provide a safe working environment for its employees and that it had breached that duty by failing to do so. The Court also held that the company was liable for the damages suffered by Sullivan as a result of its negligence. The decision in Sullivan v. Portland and Kennebec Railroad Company established the principle that employers have a duty to provide a safe working environment for their employees. This decision has been cited in numerous cases since then and has been used to support the idea that employers must take reasonable steps to ensure the safety of their employees.

In Sullivan v. Portland and Kennebec Railroad Company, the Supreme Court was asked to decide whether a railroad company could be held liable for damages caused by its negligence in failing to provide adequate safety measures on its premises. The majority opinion of the court found that it could not, as there were no applicable statutes or regulations governing such matters at the time of the incident. Justice Field dissented from this decision, arguing that while there may have been no specific laws regarding safety requirements at railroads during this period, common law principles should still apply and hold companies accountable for their negligent actions which cause harm to others. He argued that since these companies are engaged in activities with potential risks to public health and safety they should be expected to take reasonable steps towards preventing foreseeable injuries due to their operations. Furthermore he noted that allowing them immunity would create an unfair advantage over other businesses who must comply with existing laws concerning public welfare and safety standards