Wiretaps require a court order based on a showing of probable cause.  A three-step process must be followed to obtain a court order:

1. The law enforcement officer conducting the investigation must prepare a detailed affidavit demonstrating that there is probable cause that the target telephone is being utilized to facilitate a “specific, serious, indictable crime”.

2. The prosecuting attorney for the federal, state, or local government must
work with the law enforcement officer to prepare an “application” for a
court order, based upon the officer’s affidavit.  If the investigation federal,
the application must be approved by the Attorney General, Deputy
Attorney General, Associate Attorney General, any Assistant Attorney
General, any acting Assistant Attorney General, or any Deputy Assistant
Attorney General in the Criminal Division designated by the Attorney
General.  If the investigation is being conducted on the state level, the application must be prepared and approved by the State Attorney General, district attorney or county prosecutor).

3.   The attorney must present the approved application to a federal or state judge who is authorized to issue a court order for electronic surveillance.

A court order is typically issued after a lengthy investigation and
the use of a Dialed Number Recorder or “DNR”.  The DNR is used to track
the outgoing calls from the suspect’s phone in order to demonstrate
that the targeted suspect is conducting criminal activity. .