It is legal for authorities to tap a cell phone if they obtain a wiretap order, according to Perlmutter and McGuinness, P.C. Law enforcement officials must prove to a judge that they have probable cause to believe that a wiretap could reveal evidence related to a felony.
Some law enforcement officials use stingrays, also known as cell-site simulators, swamp boxes or IMSI-catchers, to collect cell phone data, explains Wired. Some of these devices can intercept cell phone conversations and text messages, but the U.S. Department of Justice says that law enforcement cannot legally use stingrays to tap cell phones without having an existing wiretap order. However officials may make exceptions to this rule under exceptional circumstances that constitute an emergency. In these cases, officials should apply for a wiretap order within 24 hours of beginning the wiretap.