Cruiser rules meet the realities of commerce attack

English Admiralty courts reach back to Edward III in the fourteenth century. Prize disputes therefore have a much deeper legal history than the comparatively recent cruiser rules. Those rules generally require warning an unarmed ship, permit stop-and-search for contraband, and demand protection for crews when a vessel is seized or destroyed. Admiral Graf Spee's treatment of captured crews tests the theory, as does the harder problem facing First World War submarines. A surfaced submarine has little room for prisoners and becomes vulnerable while searching a merchant ship, so practical commerce attack repeatedly produces decisions that later return to Admiralty courts.