Maryland Court Finds Evidence & Testimony Related to Cell Tower Drive Test Unreliable and Inadmissible

Two days ago, the Court of Special Appeals of Maryland issued an interesting opinion in Phillips v. State. In Phillips, Bashunn Phillips was charged with the first-degree murder of Shar-Ron Mason and related crimes. 

In response, Phillips filed a motion in limine, “seeking to exclude the RF signal propagation map and related testimony.”

In support of this argument,

William Folson testified for the defense that the State’s use of the drive test was not generally accepted in the forensic science community….At the time of his testimony, Mr. Folson was a professor of digital forensics and a doctoral student in information assurance, with a focus in digital forensics….He was also board certified in digital forensics, certified in cyber forensics, and certified in cellular technology and mobile evidence….Mr. Folson testified that drive tests were “a waste of time” for forensic purposes, because radio frequency signals constantly change due to such variables as weather, topography, the amount of cell phone calls being made in a particular area, the power output of a cell phone tower, the type of antenna used on a tower, foliage, and surrounding buildings….Moreover, coverage areas of different cell phone towers may overlap….[According to Folson:]

[R]adio frequency signals…fluctuate. They get stronger, they get weaker in real time. So, there is no way to calculate what the signal strength was ten months prior doing a drive test….So, that drive test is a snap shot of the [radio frequency] footprint for that tower at the time the test is done. It has nothing to do with what the [radio frequency] signal footprint was ten months prior to that test being performed.

Mr. Folson further testified that he was unaware of any peer-reviewed scientific articles or reported Maryland appellate case supporting the use of drive tests for determining the radio frequency of a cell phone tower on a certain date in the past….[According to Folson:]

We know that the cell phone companies use drive testing, and I would absolutely agree that a drive test has value to a cell phone company. However, you’re taking a drive test and you’re repurposing this diagnostic tool for a forensic methodology that has never been suggested to peer review and has never been accepted by the scientific community. That’s the issue.

Based upon this testimony, the trial judge “concluded that the State did not establish that drive tests as used by the FBI are generally accepted in the digital forensic science community”*and therefore deemed the propagation map and related testimony inadmissible.

The State responded by seeking “in banc review of the order granting Phillips’s motion in the circuit court.” The State was actually granted such review, on that review led to the trial judge’s conclusions being reversed. In turn, Phillips appealed to the Court of Special Appeals of Maryland, which issued its opinion two days ago. According to the three judge panel (including Judge Graeff, one of the judges handling the appeal in the Adnan Syed case), “the State had no right to appeal from the trial court order granting Phillips’s motion in limine,” so the in banc panel was without jurisdiction.”

As a result, the court reinstated the trial judge’s order deeming the evidence related to the drive test inadmissible and remanded the case back down to the trial court so that FolsonPhillips’s trial can be held…without the drive test evidence.

Of course, anyone following the Adnan Syed case knows that a drive test was part of the State’s case against Adnan; indeed, it was part of “the crux” of the State’s case according to Judge Welch. Because the Court of Special Appeals didn’t reach the merits of the drive test claim in Phillips, it didn’t create a new precedent that could be cited by the defense at a new trial or on appeal. But the Phillips case certainly provides a good indication that anything connected to the drive test by the State’s cell tower expert in Adnan’s case could be deemed inadmissible if a new trial is held.

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*The judge also “mused that, even if the drive test were considered generally accepted and reliable, the State’s experts were not qualified to testify because they were not members of the digital forensic science community and failed to satisfy the requirement of Maryland Rule 5-702.”

-CM