Definition - What does Wiretapping mean?
Wiretapping is accomplished when a person connects a listening device to a telephone line owned and used by someone else for the purpose of listening to their conversations without their knowledge. The police are able to wiretap an individual's phone line if a warrant is obtained. When a private company or individual does this, it is illegal although many companies do record everything that is spoken over their telephone lines. As long as the company tells the callers that the call is being recorded, it is not considered wiretapping.
Justipedia explains Wiretapping
Police will often employ wiretapping to gain information on criminal activity that can be followed up on; such information can be held up in a court of law as evidence. When a person discovers that their privacy has been breached through wiretapping, they are able to take civil action against the perpretrator as a breach of an individual's privacy is in contradiction to US civil rights.