The State of Rhode Island vs. The State of Massachusetts was a case heard before the United States Supreme Court in 1839. At issue was whether or not the state line between Rhode Island and Massachusetts should be altered due to changes in water levels over time, which had caused some land previously belonging to Rhode Island to become part of Massachusetts. After hearing arguments from both sides, the court ruled that while it could not alter an existing boundary line between two states without their consent, it did have jurisdiction over disputes concerning boundaries when they were unclear or uncertain. In this case, since there had been no agreement as to where exactly the border lay at any given point in time due to changing water levels, the court found that it could make a determination as to what constituted “the true boundary” between these two states and ordered them both into arbitration with each other so that they might come up with an equitable solution for all parties involved.

In the case of The State of Rhode Island vs. The State of Massachusetts, Justice McLean delivered a dissenting opinion in which he argued that the Court should not have decided on this matter as it was an issue between two states and therefore outside its jurisdiction. He further stated that if Congress had intended for such matters to be resolved by the Supreme Court then they would have provided specific instructions to do so in their Constitution or laws. Additionally, he noted that even if Congress had given authority to decide upon these issues, there were no facts presented before them from either state which could support a decision being made one way or another. Ultimately, Justice McLean concluded that since neither party submitted any evidence regarding ownership rights over Narragansett Bay and its islands, it was impossible for the court to make a ruling on this dispute without more information from both sides.