March law (Anglo-Scottish border)

March law (Anglo-Scottish border) (or Marcher law, or laws and customs of the marches) was a system of customary international law dealing with cross-border dispute settlement, operating during the medieval and early-modern periods in the area of the Anglo-Scottish border or Anglo-Scottish marches. The word "march" is the Old English form of the Old French word "marche" meaning "boundary", and its use was not unique to the Anglo-Scottish border - the Anglo-Welsh border and the Anglo-Irish marches had their own versions of "the Law of the Marches".

Source: Wikipedia — March law (Anglo-Scottish border) (CC BY-SA 4.0)