Definition - What does Wiretap mean?
A wiretap is the act of breaking into a person's communication line for the purpose of adding a listening device. The act of installing the device is considered the wiretap. This could happen on any type of telecommunication wire. This is only legal for the government to do when a warrant is first obtained. The purpose of the wiretap is to gain honest intelligence from sources that are not predisposed to being honest about their activity due to a criminal nature of the activity. If a person or company performs a wiretap on an individual person, it is always considered illegal.
Justipedia explains Wiretap
Only the government, through the police with the prior consent of a judge in every individual instance, can install a wiretap. Intelligence taken from a wiretap that was completed after a warrant was obtained can be admissible in court and can be used to follow other leads. If a lead is taken on the back of a wiretap that is legally made, any evidence found through following that individual lead can also be followed up by the police.