“Cellphone data is like digital DNA,” Engelbrecht explained. A court case on the precision of this technology makes that claim difficult to dispute. In response to the 2016 Supreme Court case, Carpenter v. United States, Justice Roberts wrote a 2018 opinion in which he describes the level of precision tracing afforded by pinging a cellphone using geofencing technology. “Accordingly, when the Government tracks the location of a cell phone,” writes Roberts, “It achieves near perfect surveillance as if it had attached an ankle monitor to the phone’s user.” Two of the most striking paragraphs from his 2018 opinion are captured below:

https://casetext.com/case/carpenter-v-united-states-67