Cell Phone Location – Challenging the Factual Basis Under Prong One

Challenging The Factual Basis Of Historical Cell Site/Tower Location Opinion Evidence Under Rule 5-702

Cellular service has become an integral part of our daily life.  But it does not follow from our user experience with reliable cellular service that historical location information derived from call detail records is similarly reliable.  (This blog does not address location data from a GPS chip located on the phone to enhance 911 services.) Our concern is the uncritical acceptance under Rule 5-702 of two assumptions that form the factual basis for historic location expert opinion testimony:  1) that the method used to collect historic call data on an individual basis from the carrier’s records is reliable; and 2) that the method used to interpret the data reliably determines the historical location of an individual phone in reference to a particular tower and sector, or to an area within a sector.  More on prong 2 in another post.

In relation to the first prong, in the daily course of operating a cellular network, carriers generate enormous amounts of data.  The aggregation of this data in real-time enables carriers to optimize network capacity by smoothing out or redirecting digital traffic jams of users among various cell sites. To be sure, a reliable customer experience confirms the reliability of data used in the daily operation of the cellular network.  But the reliability of data for the purpose of optimizing network operations is not a warranty of reliability for the methods used to query historical data about an individual phone.  The extraction of historic data on an individual basis is simply not an integral part of a carrier’s real-time operation of its network.  Rather, the business purpose served is to comply with a request of law enforcement. Although that may constitute a “business purpose” under the rules of evidence, a judicially created business purpose is a far less persuasive guaranty of trustworthiness. It is telling that a recurring question raised in civil litigation involving carriers and resellers of telephone service is the trustworthiness of historic call detail information.

The anecdotal experience of law enforcement cannot fill this gap.  Further, the lack of open and transparent access into the operation and inefficiencies of the cellular networks limits the ability of the defense and court to meaningfully assess the reliability of the method used to extract historic location data on an individual basis.

Contact RaquinMercer to consult with Steve Mercer about challenging cell phone location data in your case.