The Limitations and Admissibility of using Historical Cellular Site Data to Track the Location of a Cellular Phone

Aaron M. Blank, Rosenberg & Fayne, LLP

Abstract

The Limitations and Admissibility of using Historical Cellular Site Data to Track the Location of a Cellular Phone

by Aaron Blank

Imagine a crime has just been committed. Shortly thereafter, law enforcement responds and quickly apprehends a suspect close by. Combining this with testimony or physical evidence may provide enough to obtain a conviction. Now imagine a longer, more complex investigation where a suspect is neither identified nor apprehended for days, weeks, or even months until after the crime. Law enforcement gathers some evidence but it is not enough for a conviction. If the prosecution can place the suspect in the vicinity of the crime scene at the time it occurred then maybe it could corroborate other evidence to establish guilt. But if physical evidence or witnesses cannot place the suspect at the crime scene then how else can this happen?

Law enforcement is now attempting to place suspects at crime scenes by analyzing their cell phone records at relevant dates and times. When a cell phone call is made , it is routed through a cell site located at a fixed geographic location and cellular companies keep records reflecting this activity. Ideally, law enforcement would like to interpret this information to place the suspect at the scene of the crime. However, it is not always possible to do so to such a precise degree. Additionally, the subsequent testimony for cellular phone tracking may have limits on admissibility into evidence at trial.

This article explores the limitations and admissibility of using historical cell site data to prove the location of a cell phone at the time a crime was committed. This article begins with an overview of how a cellular network works, the various ways that a cell phone can be used to track its location, and the limitations of using historical cell site data as a tracking method. Next this article analyzes the admissibility of historical cell site data under the Federal Rules of Evidence, supplemented by various state court opinions, including relevance, admission through lay witnesses, and admission through experts. This article then discusses the constitutional implications of law enforcement seizing cell site data for a person’s phone and presentation as evidence in a criminal trial.

This article concludes historical cell site data can be a useful investigative tool when its limits are properly recognized. Such data can be properly used to determine the general coverage area from which a phone call was placed from but not the precise location within that area. Similarly this information can show that a call was not made from a certain area, perhaps in a way to debunk an alibi defense.

In terms of admissible testimony, the article concludes that lay witnesses should only be allowed to testify to information that is generally known concerning cell phones such as information contained in cell phone bills. Any analysis used to infer location from cell phone records should only come in through an expert. When challenging an expert, the objecting party should consider the relevance, the expert’s qualifications, and reliability of the principles applied in the expert’s analysis. If ruled admissible, the objecting party should vigorously cross-examine the expert on methodology to expose its accuracy limitations and the many factors that affect how a cell phone connects along a cellular network.

Constitutional challenges to cell site data are limited. Cell phone records are admissible as nontestimonial business records and will only raise Confrontation Clause concerns if they can be shown to be created to prove a past fact for the purpose of prosecution. Fourth Amendment precedent is split and parties should be aware that arguments exist for and against extending protection to cell site data.