The United States Supreme Court case of The United States v. Frances P. Fatio's and Louisa Hallowes' Heirs involved a dispute over land in Florida that had been granted to the two women by Spain prior to its cession of the territory to the U.S. in 1819, with title being confirmed by Congress in 1822. The government argued that since it was not specified who would inherit this grant upon their deaths, it reverted back to them as sovereign power when they died without heirs or devisees; however, their respective heirs claimed ownership based on Spanish law which allowed for inheritance rights even if no will was made at death. Ultimately, the court sided with the claimants and held that under Spanish law they were entitled to succeed as rightful owners of these lands due to succession laws regardless of whether there was a will or not at death because such an interpretation is consistent with international law principles regarding property rights between nations during times of transition from one sovereignty to another .

In the case of The United States v. Frances P. Fatio's and Louisa Hallowes' Heirs, the Supreme Court was tasked with determining whether or not a certain piece of land in Florida belonged to the United States or to two heirs who had inherited it from their mother. The majority opinion held that since no one had ever been able to prove title over this land, it should be considered public domain and thus belong to the government; however, Justice McLean dissented on this point. He argued that while there may have been some uncertainty as to who owned the property at first glance, upon further examination it became clear that both Fatio's and Hallowes' heirs were indeed rightful owners due to their inheritance from their mother prior to Spain ceding Florida back over into American hands in 1821 - an event which would normally invalidate any previous claims made by Spanish citizens such as her. Thus he concluded that they should be allowed ownership rights despite any lack of proof presented during trial proceedings