The principle that the state may not take a person's life, liberty, or property without fair procedure — notice of the charge, a hearing before a neutral judge, the chance to answer, and punishment only by settled law rather than by decree. It is the quiet machinery that stands between every individual and the raw power of the state.
Better that ten guilty persons escape than that one innocent suffer. That old maxim is not a slogan against punishment; it is the deliberate price due process agrees to pay. The principle holds that the state must follow fair, known procedures before it takes your freedom, your property, or your life, and it would rather let the guilty walk than risk crushing the innocent by shortcut. That is the difference between a trial and a lynching, between law and a ruler's whim, and it is the first protection that fear, war, and emergency teach governments to suspend.