The Mutual Reserve Fund Life Association v. Hamlin case in 1890 revolved around the issue of whether a life insurance policy could be voided due to misrepresentation or concealment by the insured party. The plaintiff, Mutual Reserve Fund Life Association, argued that they were misled by Mr. Hamlin who had failed to disclose his full medical history when applying for an insurance policy with them. They claimed this was grounds for rescinding the contract and refusing payment upon Mr. Hamlin's death. However, the Supreme Court ruled in favor of Mrs. Hamlin (the defendant), stating that while it is crucial for applicants to provide accurate information during underwriting processes, insurers also have a responsibility to conduct thorough investigations before issuing policies if they wish to avoid such risks. In essence, since there was no evidence proving intentional fraud on Mr.Hamlin's part and considering he answered all questions truthfully based on his knowledge at that time; plus given Mutual Reserve did not make further inquiries into his health status despite having opportunities - their claim was dismissed.

In the dissenting opinion for Mutual Reserve Fund Life Association v. Hamlin, 1890, it was argued that the New York law requiring out-of-state insurance companies to maintain a certain level of reserves did not violate the Constitution's Commerce Clause. The justice believed that states have an inherent right to regulate businesses within their borders and protect their citizens from potential financial harm caused by underfunded insurance companies. He contended that this regulatory power should extend even to interstate corporations operating within state lines. This view held that such regulation does not constitute an undue burden on interstate commerce but is rather a legitimate exercise of state police powers aimed at safeguarding public welfare and ensuring fair business practices in industries like insurance where consumers' interests are particularly vulnerable.