In Mastrocola v. Southeastern Pennsylvania Transportation Authority, 941 A.2d 81 (Pa. Cmwlth. 2008), the Court explained: The principle of federal preemption of state law is derived from Article VI, Clause 2 of the United States Constitution, i.e., the Supremacy Clause. Under the Supremacy Clause, federal law is the supreme law of the land and any conflicts between federal and state laws must be resolved in favor of federal law. Krentz v. Consolidated Rail Corporation, 589 Pa. 576, 595, 910 A.2d 20, 31-32 (2006). In Office of Disciplinary Counsel v. Marcone, 579 Pa. 1, 855 A.2d 654 (2004), the Pennsylvania Supreme Court explained preemption as follows: There are three ways in which a state law may be preempted. First, state law may be preempted where the United States Congress enacts a provision which expressly preempts the state enactment. Likewise, preemption may be found where Congress has legislated in a field so comprehensively that it has implicitly expressed an intention to occupy the given field to the exclusion of state law. Finally, a state enactment will be preempted where a state law conflicts with a federal law. Such a conflict may be found in two instances, when it is impossible to comply with both federal and state law or where the state law stands as an obstacle to the accomplishment and execution of the full purposes and objectives of Congress. Id. at 17, 855 A.2d at 664. Mastrocola, 941 A.2d at 88-89.