Oscar Jones (plaintiff) was boarding a bus operated by the Port Authority of Allegheny County (PAT) (defendant) when the bus suddenly lurched forward, then stopped. Jones’s arm was injured. He and his wife Mary (plaintiff) sued PAT for negligence in a Pennsylvania state court. At trial, the judge instructed the jury that the standard of care owed by PAT to its passengers was that degree of care that PAT held itself out as possessing given its status as a commercial transportation provider with the knowledge and training to transport passengers safely. The court noted that PAT’s standard of care was different than the standard applicable to an ordinary person. The jury found in favor of PAT, and the court entered judgment accordingly after denying the Joneses’ post-trial motions. The Joneses appealed.