Friday, January 9, 2009

Relevancy of GPS evidence under 904.01 Opponent

A GPS track may be constitutionally collected. A GPS track may be accurate. A GPS track may depict a time frame that included the events that the case is about. And yet, a GPS track might not be admissible because the track is not relevant. Wis. Statutes 904.02 admits all relevant evidence; 904.01defines "relevant evidence" as "evidence having any tenancy to make the existence of any fact that is of consequence to the determination of the action more probable or less probable than it would be without the existence of the evidence."

How can a track that depicts a relevant time frame not be relevant? Track users often forget that the “line of travel” that tracks depict is just an estimation of travel between a line of points. The line does not really exist, only the track points. Depending on the issue the fact finder must decide, these track points may be too far apart to give the judge or jury relevant information, and thus the entire track should be excluded.

For instance, if the issue is whether the tracked vehicle ran a stop light, a single track point that falls 4 minutes before the accident and second that falls two minutes after the accident would likely have little relevance to the timing of the accident. However, a two-second track-point track in the same situation would have relevant, but not conclusive, information for the jury, especially if the track showed the tracked vehicle stopped at the light.

Imagine the issue in the photo above (courtesy of GPS Insight is which of the two roads visible the defendant traveled to get to point “A”. The 2 minute track (red) clearly doesn't give that information, while the 3 second track of the same vehicle shows the driveway stop happened. Accordingly, the 2 minute track would not be relevant. However, if the issue is defendant's denial of driving anywhere near the area, both tracks would be relevant, as both tracks place the defendant's vehicle in the area.1

Therefore, the first question should be, what is really the issue GPS evidence is intended to address? While it is high tech, and has the “CSI” sexy factor, it may not be able to prove any disputed fact in the case, and therefore may have no relevance. Second, if GPS evidence in general can address the disputed issue, does the proffered track in particular have the ability to address the issue? The answer can be a flat no (GPS evidence not relevant, and should be excluded), clearly yes (admit the GPS evidence), or a close call (allow the evidence to be admitted and let the parties argue its relevancy to the jury).

A jury can be pretty unforgiving of "overkill". A few years ago, I heard about a case where the police had very convincing evidence of a felony, but also tried to convict the defendant of using a specific vehicle to commit the felony in the same case. The defendant didn't present any exculpatory evidence on the principle charge, but presented an airtight defense to the use of the specific vehicle. When the defense counsel finished his case, he asked the jury, in essence “If the State was so sure of this vehicle charge, and got it so wrong, what else did they get wrong? Can you be sure beyond a reasonable doubt?”

My point is, using GPS evidence that is arguably irrelevant might backfire, as if the jury figures out, or the defense correctly points out how meaningless it is, the proponent will be in danger of the jury asking “Is this all they have? How weak is their case if they are relying on this?”

1This photo does not depict any actual crime scene, but was created to show the difference between "dense" track-points and less frequent track-points in general transportation use. See

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