The abhorrence of society to the use of involuntary confessions does not turn alone on their inherent untrustworthiness. It also turns on the deep-rooted feeling that the police must obey the law while enforcing the law; that, in the end, life and liberty can be as much endangered from illegal methods used to convict those thought to be criminals as from the actual criminals themselves.

Writing for the court, Spano v. New York 360 U.S. 321 (1959)