The poorest man may in his cottage bid defiance to all the forces of the Crown. The storms may enter, the rain may enter, but the King of England cannot enter. All his forces dare not cross the threshold. -- William Pitt in the House of Commons, 1760.
Noble words, but in America at that time, the above sentiment was often honored in the breach. It was, in fact, the English practice of ignoring the sanctity of colonists' living quarters that helped bring on the Revolution. Citizens were compelled to provide English troops free room and board in their cottages on occasion. Even more demeaning to the colonists was the practice of English officials using "general warrants" and "writs of assistance," which allowed searches of homes for anything incriminating without reason and without a judicial officer determining that this was proper.
Out of repugnance for these practices came the Third and Fourth Amendments. The Third forbids the quartering of troops in peacetime in any house without the consent of the owner, or in wartime without enactment of a law. The Fourth forbids "unreasonable searches and seizures," requires that judges issue search warrants only if there is probable cause a crime has been committed and limits the search to items and places described in the warrant. There has never been a case arising under the Third Amendment. The Fourth has been invoked countless times when law enforcement officials or judges have behaved improperly -- or would have if the amendment had not existed.