In Maryland Insurance Company v. Le Roy, Bayard & M'Evers, the Supreme Court of the United States ruled that a contract between two parties must be performed according to its terms and conditions. The case involved an insurance policy issued by Maryland Insurance Company to Le Roy, Bayard & M'Evers for goods shipped from Baltimore to New York City. When some of the goods were damaged in transit due to bad weather, Le Roy attempted to recover damages under their policy with Maryland Insurance Company but was denied because they had not paid additional premiums required for coverage against losses caused by storms or other perils at sea. The Supreme Court held that since both parties agreed upon specific terms and conditions when entering into the contract, those terms could not be altered without mutual consent; thus denying recovery on grounds outside of what was specified in their agreement violated public policy and constituted a breach of contract.

In the case of Maryland Insurance Company v. Le Roy, Bayard & M'Evers, Chief Justice Marshall delivered a dissenting opinion in which he argued that the Court should not have granted judgment for the defendants on their plea to jurisdiction. He reasoned that although it was true that there had been no service of process upon them as required by law, they were still bound to answer and defend against any suit brought against them because they voluntarily appeared in court and submitted themselves to its jurisdiction. Furthermore, Marshall contended that even if service had been made according to law but without effect due to some defect or irregularity therein, this would not necessarily prevent a defendant from being held liable for failing to appear and answer when called upon by the court. In conclusion, he concluded that since all parties involved had agreed before trial began on matters pertaining thereto such as pleadings and evidence adduced at trial; then it could be reasonably assumed that those same parties also consented implicitly or explicitly with respect to issues concerning jurisdiction over them as well.