In the twenty-first year of James I. a bill had been passed giving a secure tenure of their estates to all grantees of crown lands whose possession of them had lasted sixty years.

Marshall held that this contract ran with the land, and inured to the benefit of grantees from the Indians.

In so far it approached the asientos of the full type which became the regular recourse of the Spanish government in the following centuries; but it fell short of the ultimate plan by failing to bind the grantees to the performance of their undertaking and by failing to specify the grades and the proportion of the sexes among the slaves to be delivered.