 Several influential decisions of the House of Lords have determined the limited scope for the use of prerogative powers . In 1915 , an appeal was made to the House of Lords , Re <unk> of Right ( ' <unk> Aerodrome Case ' ) , but during the appeal the case was settled and the appeal withdrawn when the Crown agreed to pay compensation . The appeal was from a unanimous decision of the Court of Appeal that the Crown , both under the statutory Defence of the Realm Regulations and by the royal prerogative , was entitled to take and occupy , for military purposes in wartime , a commercial airfield on the south coast . The government argued that this action was to defend against an invasion ; the courts held that for the prerogative to be exercised , the government must demonstrate that a threat of invasion exists . This was backed up by The <unk> ( 1916 ) , where the Privy Council , on appeal from the Prize Court , held generally that to exercise a power not granted by statute ( such as a prerogative power ) the government must prove to the court that the exercise is justified . The next decision came in Attorney General v De <unk> 's Royal Hotel Ltd ( 1920 ) , where the House of Lords confirmed that a statutory provision in an area where prerogative powers are in use " <unk> the Royal Prerogative while it is in force to this extent – that the Crown can only do the particular thing under and in accordance with the statutory provisions , and that its prerogative power to do that thing is in <unk> " . 
