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Cellphones, Law Enforcement, and the Right to Privacy

Summary: This paper surveys the landscape of government acquisition of location data about cell phone users, how that location information is accrued and disseminated, and the technologies that can establish past and present locations, and identify other users in proximity.

Published: December 20, 2018

Exec­ut­ive Summary

Cell phones are ubiquit­ous. As of 2017, there were more cell phones than people in the United States. Nearly 70 percent of those were smart­phones, with 94 percent of millen­ni­als carry­ing a smart device. Cell phones go nearly every­where, and users are increas­ingly depend­ent on smart­phone applic­a­tions for daily activ­it­ies, such as texting, email, and loca­tion-assisted direc­tion services. 

Cellu­lar tech­no­logy also allows service providers to collect a wealth of inform­a­tion about a user’s where­abouts. Cellu­lar service providers auto­mat­ic­ally record the loca­tion of cell phones at regu­lar inter­vals, trans­form­ing them into personal track­ing devices. One court described them as the “easi­est means to gather the most compre­hens­ive data about a person’s public — and private — move­ments.” Cell phone loca­tion data is collec­ted in such high volume that it offers a nearly inex­haust­ible source of gran­u­lar inform­a­tion, includ­ing when and where someone goes, with whom, and even for what purpose. 

This white paper surveys the land­scape of govern­ment acquis­i­tion of loca­tion data about cell phone users — from cellu­lar providers’ collec­tion of loca­tion inform­a­tion to the use of tech­no­lo­gies that pinpoint where indi­vidu­als and cell phones are located. It describes how cell phones oper­ate, how that loca­tion inform­a­tion is accrued and dissem­in­ated, and the tech­no­lo­gies that can be used to estab­lish where a phone is, where it has been, and what other users have been in prox­im­ity. 

The paper then analyzes both the legal and policy land­scape: how courts have ruled on these issues, how they can be expec­ted to rule in the future, and how agen­cies have addressed these issues intern­ally, if at all. It adds to concerns that cell phone-based monit­or­ing could viol­ate the consti­tu­tional privacy rights of millions of ordin­ary Amer­ic­ans — and that people of color are dispro­por­tion­ally affected. Finally, it concludes with a set of recom­mend­a­tions to enhance trans­par­ency and account­ab­il­ity around the use of cell phone loca­tion data and to ensure consti­tu­tional protec­tions for users who are affected.