In Conn et al. v. Penn, the Supreme Court of the United States was asked to decide a dispute between two states over land boundaries and ownership rights in what is now Kentucky and Tennessee. The case involved a 1780 Virginia grant that had been made to William Conn for lands located within the borders of Kentucky at that time, which were then part of Virginia but later became part of Pennsylvania after it ceded its western territory to Congress in 1784. The court held that although Pennsylvania had acquired title from Virginia by virtue of its cession, this did not affect any existing grants or titles already vested in individuals prior to such transfer; thus, William Conn's original grant remained valid despite subsequent changes in state boundaries. Furthermore, because all parties agreed that no other individual or entity could claim superior title over those granted by Virginia before her cession took effect, the court concluded that Mr. Conn was entitled to his full estate as originally granted under Virginian law without interference from either state government thereafter.

In Conn et al. v. Penn, the Supreme Court was tasked with determining whether a state could be sued in federal court by citizens of another state without its consent. The majority opinion held that states were immune from such suits and thus dismissed the case against Pennsylvania brought by Connecticut residents. However, Justice Story dissented on this point, arguing that while it may have been true at one time that states enjoyed sovereign immunity from suit in federal courts, this had changed due to the adoption of the Constitution which established a new system of government where each branch is limited in power and subject to checks and balances imposed by other branches as well as individual rights protected under law. He further argued that if Congress had intended for states to remain immune from suit then they would have included language explicitly granting them such protection when drafting laws or amending existing ones; however no such language exists so he concluded there was no legal basis for denying individuals their right to sue a state in federal court without its consent.