The Fourth Amendment embodies a fundamental truth and the chief characteristic distinguishing a free society from a tyrannical police state. An individual’s right to privacy and freedom from arbitrary invasions cannot be infringed, unless probable cause “exist[s] where the known facts and circumstances are sufficient to warrant a man of reasonable prudence in the belief that contraband or evidence of a crime will be found” (Ornelas v. United States, 517 U.S. 690, 696, 1996). 
 
After having successfully prosecuted Nazi war criminals at Nuremberg, former U.S. Supreme Court Justice Robert Jackson eloquently reaffirmed the importance of this safeguard against unbridled governmental intrusion: 
 
Uncontrolled search and seizure is one of the first and most effective weapons in the arsenal of every arbitrary government. And one need only briefly to have dwelt and worked among a people possessed of many admirable qualities but deprived of these rights to know that the human personality deteriorates and dignity and self-reliance disappear where homes, persons and possessions are subject at any hour to unheralded search and seizure by the police (Brinegar v. United States, 338 U.S. 160, 180–181, 1949). 
 
And then came Richard Nixon’s “War on Drugs.”