The Reciprocal and Mutual Duty Betwixt a Free King and His Natural Subjects (original Scots title: The Trve Lawe of free Monarchies: Or, The Reciprock and Mvtvall Dvtie Betwixt a free King, and his naturall Subiectes) is a treatise or essay of political theory and kingship by James VI of Scotland (later to be crowned James I of England too). It is believed James VI wrote the tract to set forth his idea of kingship, in contrast to the contractarian views espoused by, among others, George Buchanan (in De Jure Regni apud Scotos, 1579). James VI had the work published in 1598. It is considered remarkable for setting out the doctrine of the divine right of kings in Scotland, and latterly England, for the first time. James saw the divine right of kings as an extension of the apostolic succession.