M'Millan v. M'Neill was a case heard by the United States Supreme Court in 1819 that dealt with the issue of whether or not a state court had jurisdiction to hear an action brought against someone from another state. The plaintiff, M’Millan, argued that he should be allowed to sue his former business partner, M’Neill, who lived in North Carolina but conducted business in South Carolina. The defendant argued that since he did not reside within the same state as where the suit was filed and thus could not be sued there. Ultimately, Chief Justice John Marshall ruled for M’Millan on grounds of diversity jurisdiction which allows federal courts to hear cases between citizens of different states when certain conditions are met. This decision established precedent for future cases involving similar issues and helped define how far-reaching a court's jurisdiction can extend across borders into other states

In M'Millan v. M'Neill, the Supreme Court was asked to decide whether a contract between two parties could be enforced if it had been made without consideration. The majority opinion held that such contracts were unenforceable because they lacked mutuality of obligation and consideration. However, Justice Story dissented from this decision on the grounds that there is no legal requirement for consideration in order to make an enforceable contract; rather, he argued that a valid agreement can exist even when one party has not received any benefit or detriment in exchange for their promise. He further reasoned that since both parties agreed to enter into the contract voluntarily and with full knowledge of its terms, it should be considered binding regardless of lack of consideration.