Leges Marchiarum — Laws of the Marches (c. 1248)

The Laws of the Marches governed the borderlands between England and Scotland from the thirteenth century until union in 1707. Administered through joint Days of Truce — formal meetings of English and Scottish wardens — the March laws created a cross-border dispute resolution system that operated outside and between two sovereign jurisdictions. Neither crown could unilaterally impose its law; instead, a bilateral customary framework evolved through practice and consent. A historical example of polycentric, inter-jurisdictional law functioning in a contested sovereignty zone.