Baltimore & Ohio Railroad v. Commonwealth

*73OPINION OF THE COURT

ROBERTS, Justice.

As a result of an administrative proceeding commenced by appellant United Transportation Union, appellee railroads were directed to adopt weekly pay periods for certain of their employees, as required by Pennsylvania Act No. 43 of 1971.1 The railroads appealed this order to the Commonwealth Court, urging that the Act was invalid under the Supremacy Clause of the United States Constitution because it conflicted with the federal Railway Labor Act2 and because it invaded a field totally occupied and therefore preempted by the Railway Labor Act.3 They also…