The fundamental principles of civil liberty and the enjoyment of property forbid that one's person or premises be searched or that his person or property be seized without lawful authority; and without any express constitutional guaranty, immunity from such unlawful acts would be fully recognized. But the people of England and of the colonies had experienced unjustifiable invasion of this right by means of searches and seizures not authorized by law and in the exercise of a tyrannical authority, and it was natural that express guaranties against such tyrannical acts should be inserted in the state constitutions and in the federal constitution. The provision of the latter is as follows: "The right of the people to be secure in their persons, houses, papers, and effects against unreasonable searches and seizures shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched and the persons or things to be seized" (Amend. IV). The notion that every man's house is his castle, to be invaded without his consent only under lawful authority, which has been already referred to in the preceding chapter, is further recognized here. There maybe proper occasion for the invasion of private premises in the execution of the law, but the guaranty is as against such acts by public authority without the sanction of law. Such invasion on the part of public officers may be lawful without warrant or other process for the purpose of arresting a criminal or in the protection of the public health or safety, but the officer thus acting on his own responsibility and judgment is subject to the risk of being held accountable for trespass if in the judgment of the court the circumstances did not justify his action. He cannot safely proceed upon mere suspicion or upon his own whim or caprice. Subject to the same liability a private person may sometimes be justified in breaking into private premises to prevent a crime or arrest a criminal.

The sanctity of the person and the dwelling, which the common law fully recognizes, extends also to private books, correspondence, and other things in which the public has no legitimate concern.