As one of the documents intended to provide guidance for DOJ employees explains, triggerfish can be deployed "without the user knowing about it, and without involving the cell phone provider." That may be significant because the legal rulings requiring law enforcement to meet a high "probable cause" standard before acquiring cell location records have, thus far, pertained to requests for information from providers, pursuant to statutes such as the Communications Assistance for Law Enforcement Act (CALEA) and the Stored Communications Act.
The Justice Department's electronic surveillance manual explicitly suggests that triggerfish may be used to avoid restrictions in statutes like CALEA that bar the use of pen register or trap-and-trace devices — which allow tracking of incoming and outgoing calls from a phone subject to much less stringent evidentiary standards — to gather location data. "By its very terms," according to the manual, "this prohibition applies only to information collected by a provider and not to information collected directly by law enforcement authorities. Thus, CALEA does not bar the use of pen/trap orders to authorize the use of cell phone tracking devices used to locate targeted cell phones."http://arstechnica.com/news.ars/post/20081116-foia-docs-show-feds-can-lojack-mobiles-without-telco-help.html
Don't ask the telcos to track people's cell phones - they might record the request, and then you could get in trouble for violating constitutional privacy rights. Instead use a briefcase sized portable cell site test machine to trick the phone into giving you its location. Very clever.