Liversidge v. Anderson [1942] AC 206 (House of Lords) Background / Facts During World War II , the UK government exercised emergency powers under Regulation 18B of the Defence (General) Regulations, 1939 . Regulation 18B allowed the Home Secretary to detain a person if he had “reasonable cause to believe” that the person was of hostile associations. Robert Liversidge was detained without trial. He challenged his detention, arguing that: The Home Secretary had no reasonable grounds . Courts should examine whether the belief was objectively justified . Legal Issues What does “reasonable cause to believe” mean? Can courts review the reasonableness of the executive’s belief? How far should courts defer to the executive during wartime? Majority Judgment (4:1) Held: Detention lawful. Key Reasoning: “Reasonable cause to believe” means the Home Secretary’s subjective satisfaction , not objective review. Courts should not second-guess executive ...