For the Defense - Vol. 7, Issue 2 - 18

meters.4 According to the GAO, environmental conditions
prevent GPS technology from providing accurate location
data on a consistent basis, and this potential inaccuracy of
the data creates obstacles for criminal justice agencies in
the context of electronic monitoring. 5
Cellular service providers log and retain location
information for calls, texts, and data connections. This
stored data is known as cell site location information,
or CSLI. Such records can indicate which cell tower ( " cell
site " ) and which directional antenna of that tower
( " sector " ) the phone was connected to at the time of each
call, text, or data session. The locational precision of this
information can vary according to the broadcast coverage
of the cell site.6
In criminal prosecutions, the use of CSLI is based on
the premise that a cell phone connects to the tower in
its network with the strongest signal and/or the tower
closest to the cell phone at the time a call is placed. The
problem with this technology is that it
is incorrect to
believe that a cell phone always connects to the closest
towers. Expert testimony in other jurisdictions has made
clear that a phone may actually connect to towers miles
distant from the location,7
and indeed can connect to a
tower as far as 21 miles away.8
To date, one reported case in this Commonwealth has
addressed whether such proof is evidentiarily admissible.
The Pennsylvania Superior Court in Commonwealth
v. Nevels,9
held " that scientific evidence concerning
historical cell-site analysis is not novel " and, therefore, " its
admissibility is not subject to the requirements of Frye. " 10
However, the appellant in Nevels presented no evidence
on this issue-appellant raised the challenge, and the
prosecution presented its own expert. Proof such as that
offered in the Colorado and Alabama cases has yet to be
fully vetted in Pennsylvania.
Event Data Recorders (Black Box)
A " black box " or event data recorder can " capture...
the speed of the vehicle, its direction of travel, turn signal
activation, seat belt usage by all occupants, and the Global
Positioning System ( " GPS " ) coordinates of the vehicle at
every point in its movements. " 11
It has on occasion been
utilized in criminal prosecutions.12
The Pennsylvania Superior Court in Commonwealth v.
Safka considered a Frye challenge to the proof and rejected
the challenge as invalid based on the court's finding that
the technology was not novel.13
It did not assess the use
of black box data in the context of a reliability challenge,
although some of the Frye hearing testimony may have
focused on that. Throughout the country, courts have
admitted black box testimony. Yet, even with this well18
For The Defense l Vol. 7, Issue 2
In Commonwealth v. Weeden, a ShotSpotter report
was admitted into evidence following the detective's
testimony that ShotSpotter technology was " very
accurate " in " his experience " even though the detective
regarded form of proof, there can be errors, as described
by an expert in vehicle engineering and design:
When a vehicle impacts multiple objects, the
timing of the recorded events can be flawed
or out of sequence, as data is continually
overwritten. Impacts that compromise the
electrical system may yield bad data. Data in
the EDR comes from multiple systems, this data
can be out of sync or wrong compared to the
Airbag Control Module's timing circuit and
accelerometer(s). Newer EDRs may have the
ability to record more than one event.
EDR components can corrode over time. Also,
data can be overwritten or plain wrong if the
download is performed improperly. Collisions
and vehicle maneuvers that alter the wheel
speed relative to the actual vehicle speed can
yield misleading data. This can occur when the
vehicle goes airborne, spins, loses or locks-up a
wheel, rolls over, or is cut in half. Narrow and
light weight object impacts as well as small
overlap collisions are often either not recorded
or the data is flawed. The duration of the
impact also may exceed the recording threshold
of the EDR.14
ShotSpotter Technology
ShotSpotter technology is a claimed gunshot detection
system employed by cities throughout the country.
According to the company's website, the technology
uses " acoustic sensors to detect, locate and alert law
enforcement agencies and security personnel about
illegal gunfire incidents in real-time. " 15
Once the sensors
identify a potential gunshot, the data are sent to analysts
who determine whether the event was " in fact gunfire. " 16
Naturally, this technology has been utilized in criminal
prosecutions as evidence of the location of gunshots.17 18
The purpose of the technology is to detect gunshots,
but the sensors often produce false positive alerts when
they sense other noises, including fireworks.19
According
to a study conducted by the Chicago's Office of Inspector
General, gun-related criminal offenses were found in
only 9.1% of ShotSpotter alerts in Chicago, calling into
question the accuracy of the technology.20
While human
analysts are responsible for filtering out false positive
alerts, those results can be corrupted by human error and
even corruption.21
For the Defense - Vol. 7, Issue 2

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