Penelope McGill brought a case against Josephine H. Armour in the United States Supreme Court. The dispute was over a piece of property located in Washington, D.C., which both parties claimed to own and had been living on for some time prior to the lawsuit being filed. McGill argued that she had purchased the land from its previous owner, while Armour contended that her father-in-law had given it to her as part of an inheritance before his death several years earlier. After hearing arguments from both sides, the court ruled in favor of Armour based on evidence presented by witnesses who testified about their knowledge of how ownership was transferred between generations within their family line. This decision established legal precedent for future cases involving similar disputes over title or possession rights related to real estate transactions and inheritances throughout America's judicial system at all levels today

In the case of Penelope McGill v. Josephine H. Armour, Justice McLean delivered a dissenting opinion in which he argued that the plaintiff had not proven her right to recover damages from the defendant for breach of contract. He noted that while there was evidence presented by both parties, it did not conclusively prove either party's claim and thus could not be used as a basis for awarding damages to one side or another. Furthermore, he argued that even if the plaintiff had established her right to recover damages, she still would have been unable to do so because she failed to provide sufficient proof of actual damage suffered due to the defendant's breach of contract. In conclusion, Justice McLean stated his belief that no judgment should be rendered in this case until further evidence is provided by either party demonstrating their respective rights and obligations under their agreement with each other.