And it is also immaterial that the intrusion was in aid of law enforcement. Experience should teach us to be most on our guard to protect liberty whe… - Louis D. Brandeis

In a government of laws, existence of the government will be imperiled if it fails to observe the law scrupulously. Our Government is the potent, omnipresent teacher. For good or ill, it teaches the whole people by its example. . . . If the Government becomes a lawbreaker, it breeds contempt for law; it invites every man to become a law unto himself.

And it is also immaterial that the intrusion was in aid of law enforcement. Experience should teach us to be most on our guard to protect liberty when the Government’s purposes are beneficent. Men born to freedom are naturally alert to repel invasion of their liberty by evil-minded rulers. The greatest dangers to liberty lurk in insidious encroachment by men of zeal, well meaning but without understanding. Olmstead v. United States, 277 U.S. 438 (1928) (Brandeis, J., dissenting), overruled by Katz v. United States, 389 U.S. 347 (1967).

The protection guaranteed by the Amendments is much broader in scope. The makers of our Constitution undertook to secure conditions favorable to the pursuit of happiness. They recognized the significance of man’s spiritual nature, of his feelings, and of his intellect. They knew that only a part of the pain, pleasure and satisfactions of life are to be found in material things. They sought to protect Americans in their beliefs, their thoughts, their emotions and their sensations. They conferred, as against the Government, the right to be let alone — the most comprehensive of rights and the right most valued by civilized men. To protect that right, every unjustifiable intrusion by the Government upon the privacy of the individual, whatever the means employed, must be deemed a violation of the Fourth Amendment. And the use, as evidence in a criminal proceeding, of facts ascertained by such intrusion must be deemed a violation of the Fifth.

[Olmstead v. United States, 277 U.S. 438 (1928) (dissenting)]