In the case of Edward Prigg v. The Commonwealth of Pennsylvania, the Supreme Court was asked to decide whether a state law that prohibited citizens from removing slaves from its borders without permission violated the Fugitive Slave Clause in Article IV of the United States Constitution. At issue was whether states had authority over slavery or if it fell under federal jurisdiction. In an 8-1 decision, Chief Justice Roger Taney wrote for the majority and held that although Congress has exclusive power to legislate on this subject, states have concurrent powers as well and can pass laws regarding fugitive slaves within their own boundaries so long as they do not conflict with any acts passed by Congress. He further stated that since Pennsylvania's law did not conflict with any act passed by Congress, it was valid and constitutional. This ruling established precedent for other cases involving slavery in which state laws were challenged based on conflicting federal legislation or interpretation of Constitutional provisions related to slavery.

In the case of Edward Prigg v. The Commonwealth of Pennsylvania, the Supreme Court was asked to decide whether a state law that required citizens to assist in returning runaway slaves violated the federal Fugitive Slave Act. Justice McLean wrote a dissenting opinion arguing that Congress had exclusive authority over interstate relations and could not be interfered with by states. He argued that since slavery was an issue between states, it should be regulated by Congress alone and any attempt by individual states to regulate it would violate both constitutional principles and public policy. Furthermore, he argued that while some may disagree with this decision on moral grounds, morality cannot override legal considerations when interpreting laws or deciding cases before courts of justice.