indigenous peoples. By the eighteenth century, some leading theorists of international law argued that territorial rights over land could stem from the settlement and cultivation of that land. William Blackstone, in 1756, wrote, "Plantations or colonies, in distant countries, are either such where the lands are claimed by right of occupancy only, by finding them desert and uncultivated, and peopling them from the mother-country; or where, when already cultivated, they have been either gained by conquest, or ceded to us by treaties. And both these rights are founded upon the law of nature, or at least upon that of nations." Two years after Blackstone, Emer de Vattel, in his (1758), drew a distinction between land that was effectively occupied and cultivated, and the unsettled and uncultivated land of nomads which was open to colonization. All imperial European states enacted symbolic rituals to give notice of discovery and possession of lands to other states. These rituals included burying plates, raising flags, erecting signs, and naming territories, rivers or other features. More concrete claims of possession ranged from building forts to establishing settlements. Rituals of a transfer of sovereignty often involved trials, executions and other acts to symbolize that the laws of the colonizing power were in force. European monarchs often asserted sovereignty over large areas of non-Christian territory based on purported discoveries and symbolic acts of possession. They frequently issued charters and commissions giving the grantees the power to represent the Crown and acquire property. While European states often acknowledged that indigenous peoples inhabiting these lands had property rights which had to be acquired through conquest, treaty or purchase, they sometimes acted as if territories were uninhabited and sovereignty and property rights could be acquired through occupation. Summarizing the practices European states used to justify their acquisition of territory inhabited by indigenous peoples, McNeil states, "While Spain and Portugal favoured discovery and papal grants because it was generally in their interests to do so, France and Britain relied more on symbolic acts, colonial charters, and occupation." Benton and Strauman argue that European powers often adopted multiple, sometimes contradictory, legal rationales for their acquisition of territory as a deliberate strategy in defending their claims against European rivals. North American jurisprudence In 1792, U.S. Secretary of State Thomas Jefferson claimed that the doctrine of discovery was international law which was applicable to the new US government as well. The discovery doctrine was expounded