For the Defense - Vol. 7, Issue 2 - 17

Machine-Generated Evidence: It's
Not Frye; It's Authentication
Jules Epstein, Cheryl Brooks,
and Meredith Lowry
I
n Commonwealth v. Jamal Wallace,1
the Pennsylvania
Supreme Court allowed appeal on the question of
whether Global Positioning System ( " GPS " ) data are
hearsay. The overarching question of whether digital data
are hearsay is debatable because a hearsay statement
requires a human declarant. But hearsay is not the only
challenge to such forms of proof in a criminal trial, as
detailed in an amicus curiae brief filed by PACDL and
the Defender Association of Philadelphia. The following
article, written by the authors of the amicus brief, is a call
to arms for defense lawyers to look to the authentication
rules in particular Rule 901(b)(9)-as a means to respond
to the proliferation of digital and machine-generated
proof used in criminal trials in Pennsylvania.
The use of digital or machine-generated proof-
including GPS, facial recognition, cell-phone location
tracking, and ShotSpotter data, among many others-
has been increasingly used by prosecutors and law
enforcement in Pennsylvania. This has occurred because
technology has permeated all aspects of modern life,
and policing has adapted to the same.2
Indeed, electronic
devices not intended for investigative use are often utilized
for criminal prosecutions. As one technology article put
it, " It's no surprise that fitness wearables, mobile phones,
tablets, and other devices are the first places investigators
look regarding crimes or locations. " This means that,
more and more, key issues at trial-where an accused
was located based on wearing a parole ankle bracelet or
using a 'black box' to determine a vehicle's speed before
a deadly crash-are presented without a live witness who
has any actual knowledge of the facts or the testing of
proof via cross-examination.
Some Sample Forms of Machine-Generated Proof
GPS Location Tracking
GPS is a satellite-based navigation system made up of at
least 24 satellites. Each satellite transmits a unique signal
and orbital parameters that allow GPS devices to decode
the location of the satellite. The GPS receiver measures the
distance to each satellite by the amount of time it takes to
receive a transmitted signal.3
Despite law enforcement's reliance on this technology,
no GPS system is perfectly precise. In perfect conditions,
GPS signals provide accuracy in the neighborhood of 10
Vol. 7, Issue 2 l For The Defense 17

For the Defense - Vol. 7, Issue 2

Table of Contents for the Digital Edition of For the Defense - Vol. 7, Issue 2

Contents
For the Defense - Vol. 7, Issue 2 - 1
For the Defense - Vol. 7, Issue 2 - 2
For the Defense - Vol. 7, Issue 2 - Contents
For the Defense - Vol. 7, Issue 2 - 4
For the Defense - Vol. 7, Issue 2 - 5
For the Defense - Vol. 7, Issue 2 - 6
For the Defense - Vol. 7, Issue 2 - 7
For the Defense - Vol. 7, Issue 2 - 8
For the Defense - Vol. 7, Issue 2 - 9
For the Defense - Vol. 7, Issue 2 - 10
For the Defense - Vol. 7, Issue 2 - 11
For the Defense - Vol. 7, Issue 2 - 12
For the Defense - Vol. 7, Issue 2 - 13
For the Defense - Vol. 7, Issue 2 - 14
For the Defense - Vol. 7, Issue 2 - 15
For the Defense - Vol. 7, Issue 2 - 16
For the Defense - Vol. 7, Issue 2 - 17
For the Defense - Vol. 7, Issue 2 - 18
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For the Defense - Vol. 7, Issue 2 - 32
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For the Defense - Vol. 7, Issue 2 - 41
For the Defense - Vol. 7, Issue 2 - 42
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