Both surveillance and eavesdropping court cases have hinged upon an intrusion of the plaintiff's physical and mental solitude. The nature of much of the work of a private investigator can intrude upon the privacy of the private citizen, and the degree of intrusion permitted is an ongoing matter for the courts. The right to investigate is well established through case law, but the courts have held the investigations must be conducted within legal bounds and that there should be certain limits as to how the investigation is conducted. The courts have addressed the problem of surveillance versus the right to privacy and have concluded that although surveillance is justifiable and legal, the person under surveillance has a course for action when the investigator exceeds certain limits. The courts have held that investigators who inadvertently revealed themselves while following plaintiffs are not liable for an invasion of privacy in the absence of a showing that such surveillance was intended to harass or intimidate plaintiffs into an involuntary settlement. Cases in which plaintiffs have prevailed involved situations where the private investigator's actions were known to the plaintiff and admittedly done for the express purpose of harassment. Congress has made it an offense and also the basis for a civil suit for anyone without proper authority to tap wires used for communication and to intercept oral conversations that occur on the premises of business or commercial establishments engaged in interstate commerce; however, eavesdropping on an extension telephone with permission of one/two of the parties is permitted if allowed by State statutes and is not criminal or tortious in nature. 21 references