• David A. Cmelik Law PLC

Some, not all, cell phone tower data testimony requires experts


Police can offer some cell phone data testimony. The line between inexpert and expert testimony is tricky and depends on whether it is within the knowledge and experience of most jurors or otherwise requires expert training.

The Iowa Supreme Court examined this month whether a nonexpert police officer can offer some cell phone data testimony. Specifically, the court examined whether a detective can take cell phone data from spreadsheet for a particular tower and draw a map of a suspect’s likely whereabouts based on the range of both the tower and the phone. The Court held that drawing a circle on a map to denote the range of a cell phone tower and testifying that a phone inside that range communicated with the tower did not require an expert. It is just the sort of thing a jury would understand without expert training, held the Iowa Supreme Court.


In a criminal jury trial, an expert may offer an opinion based on specialized or scientific, technical, or other specialized knowledge. Typically, a police officer may not testify to something that is highly scientific or technical if he or she does not have specialized training. But the Iowa Rules of Evidence changed in 2017 regarding the distinction between so-called lay and expert testimony. The Boothby case was the Iowa Supreme Court's first opportunity to test that new rule in a criminal case.


Boothby was an assault case involving a car as a dangerous weapon. Police alleged the criminal defendant, Boothby, twice used his moving car to “ram” another moving car on the same road. But the victim did not get a plate number and a passenger only gave a general description of the vehicle as either a GMC “Jimmy” or Chevrolet “Blazer.”


Another witness came forward and offered his suspicion that it was the defendant. Detectives went to the defendant's house, but he denied involvement and showed police his bumper, which was detached from the front of his Trailblazer. It showed no evidence of paint transfer. Police officers thus could not yet prove the Boothby defendant was at the scene of the crime.


A detective obtained a spreadsheet from US Cellular that included data from a cell phone tower, including identifying data about communications between cell phone towers and the suspect’s cell phone. The investigation was intended to pinpoint the defendant’s whereabouts in the allegedly intentional hit-and-run case.


The spreadsheet and other data obtained by law enforcement was “self-authenticating” meaning that a records custodian swore an affidavit that it was made at or about the time of the incident in the normal course of business and that she prepared it. It was then offered in the criminal jury trial and admitted as evidence. Other information by another US Cellular employee was also included and offered without this affidavit. The Supreme Court held that some, but not all, of the information provided was indeed hearsay but was generally admissible under exceptions to the rule.


The detective testified that he printed a Google Earth map and then “plotted” the Defendant’s whereabouts using this cell phone data and the range of the cell phone tower.


Justice Oxley, writing for the court examined how other states and jurisdictions handle police who testify about cell phone tower data. She wrote that Maryland requires experts-- not everyday police officers-- to talk about cell phone towers but noted that a district court in Northern Illinois as well as a 10th Circuit Court of Appeals decision had a “more nuanced” approach.


Creating a map from Google Earth and using a compass to plot the radius of the cell phone tower’s reach appears to be “within the ken,” or, average ability, of a juror or witness, according to these federal decisions. It doesn’t require specialized knowledge to understand it, or so goes the reasoning of the federal court decisions. Therefore, it doesn’t require expert testimony to explain it, wrote Justice Oxley. But explaining how cell phones and towers transmit calls does require specialized knowledge.


According to the Court, the decisions that draw a particular line between cell phone experts and everyday witnesses made a decision about “whether the ‘process of reasoning’ utilized by the witness was one ‘familiar in everyday life’ or could ‘be mastered only by specialists in the field.’”


Missouri, Nevada, Kansas, and Ohio courts draw a similar line: plotting points on a map and determining whether a cell phone was present within a certain radius of a cell phone tower wasn’t rocket science. But explaining cell phone strength and how cell phones choose among competing cell phone towers required an expert. New Hampshire compared cell phone tower testimony to the horizontal gaze nystagmus, or, HGN, field sobriety test in a drunk driving case, stating that officers can testify how they perform the test but not the neuroscience behind it.


But the West Virginia courts rejected this line drawing exercise, noting that expert witnesses don’t just recite records—they use them to render an opinion on the ultimate fact issues before the jury, a combined task. Therefore, in West Virginia, to even discuss historical site data for cell phones, the witness must be qualified as an expert.


The Iowa Supreme Court held that, in Boothby, the detective merely testified that the cell phone had been present within a certain radius of a cell phone tower with which it communicated, a simple fact, and that the Google Earth map reflected this lay opinion testimony. He used a process familiar to everyone in daily life and his testimony was not beyond the understanding of any on the jury. It thus did not require scientific explanation to offer such testimony regarding the radio range of the cell phone and the tower.


The Court thus found that the detective did not need to be an expert to offer this testimony and affirmed the criminal jury trial conviction for assault with a dangerous weapon.


Justice Oxley, however, reiterating the Second Circuit decision that dealt with this issue, noted that the line is “frequently difficult to draw” and that expert testimony is required if the State seeks to explain something more scientific than the range of a cell phone tower on a map.


David A. Cmelik Law PLC had no involvement in the Boothby criminal appeal nor jury trial.


If you have been arrested for a criminal offense in Cedar Rapids, Iowa City, or other Iowa jurisdiction, contact us for a free initial consult.







© 2021 by David A. Cmelik Law PLC