After being injured in a collision between two trains, Robert M. Cavanaugh (plaintiff), the engineer of one of the trains, sued Western Maryland Railway Company (Western) and Baltimore & Ohio Railroad Company (B&O) (collectively, defendants) under the Federal Employers’ Liability Act (FELA). At the time of the collision, Cavanaugh was employed by Western or B&O. The collision occurred with a B&O train on B&O tracks. Cavanaugh filed his suit more than a year and a half after the accident; he sought $1,500,000 for personal injuries. Western and B&O counterclaimed for $1,700,000 in property damage alleged to have been caused by Cavanaugh’s negligence in operating the train. The railroads admitted that they rarely brought actions for property damage against their employees. Cavanaugh moved to dismiss the railroads’ counterclaim on the ground that it was barred by FELA. The district court agreed and dismissed the claim. The railroads appealed.