Summary
The Supreme Judicial Court of Massachusetts held that the trial judge abused his discretion by admitting speed measurements from the defendant's GPS ankle monitor without sufficient reliability testing or foundation. Because the error was prejudicial, the court reversed the defendant's convictions, while holding that the evidence was sufficient to support the convictions and addressing other evidentiary and constitutional issues that could arise at retrial.
Topics
Practice areas
Questions Presented
- Whether GPS speed evidence generated by the ET1 ankle-monitor device was sufficiently reliable to be admitted as expert or technical evidence.
- Whether GPS location evidence generated by the ET1 device satisfied the gatekeeper-reliability requirement.
- Whether admission of the unreliable GPS speed evidence was prejudicial.
- Whether the evidence was sufficient to support Davis's convictions.
- Whether maps depicting GPS data violated the hearsay rule or Davis's confrontation rights.
- Whether a cell-phone recording of surveillance footage was properly authenticated.
- Whether the prosecutor improperly urged the jury to identify Davis as the shooter from a low-resolution video that did not show the shooter's face.
Holdings
- When a particular model of a technical device is challenged on reliability grounds, the Commonwealth must establish that the model itself satisfies the Daubert-Lanigan or Frye reliability standard; showing only that GPS technology generally is reliable is insufficient. Because the ET1's speed-measurement capability had never been formally tested and the Commonwealth made no showing that the model used a reliable methodology or was sufficiently similar to a previously validated device, the trial judge abused his discretion by admitting the speed evidence.
- The trial judge did not abuse his discretion by admitting the ET1's location data because the Commonwealth presented formal testing showing that the device reliably applied an accepted GPS location methodology.
- Admission of the ET1 speed evidence was prejudicial error requiring reversal because the prosecutor used the speed data repeatedly to correlate Davis's movements with those of the shooter and the witness's fleeing runner.
- The evidence was sufficient to support the convictions, even though it was circumstantial and not overwhelming.
- The GPS maps did not constitute hearsay, and their admission did not violate the confrontation clauses, because the relevant latitude, longitude, speed, map, and plotted-point information was computer-generated rather than a human assertion.
- The cell-phone recording of the surveillance video was properly authenticated through circumstantial evidence, and the trial judge did not abuse his discretion by admitting it.
- The Commonwealth's opening-statement suggestions that jurors could identify Davis as the shooter from the video were unreasonable because the low-resolution video did not show facial features and depicted only common characteristics such as a Black man with long braids or dreadlocks.
Key quotations
“We conclude that the judge abused his discretion in admitting the speed evidence, where the ET1's ability to measure speed had never been formally tested. Because this error was prejudicial, we reverse the defendant's convictions.” (2-3)
“It is not sufficient to show merely that GPS technology is, in general, reliable without making any showing pertaining to the reliability of a particular model of a device.” (16-17)
“Without the speed, a jury would have only been able to infer that the defendant was in the area where the shooting took place. With the speed, however, the jury could match the defendant's movements to those of the shooter in the video and the man Rock saw, thereby presenting a compelling narrative that the defendant was the shooter.” (23-24)
“Given the shooter's common hairstyle and the inability to see any of his facial features, it was unreasonable for the Commonwealth to ask the jury to identify the defendant as the shooter in the video.” (38)
Factual background
A shooter fired multiple shots at a moving blue sedan in Boston, and surveillance footage depicted a Black man with long braids or dreadlocks wearing a red or pink shirt. Police identified Matthew Davis as a suspect because GPS data from his probation ankle monitor placed him near the shooting and purported to show movements and speeds corresponding to those of the shooter and a nearby witness. The GPS device's location function had been formally tested, but its speed-measurement capability had not. At trial, the jury convicted Davis, relying in part on the GPS speed and location evidence, the surveillance video, and witness Ilene Rock's testimony.
Procedural history
Indictments were returned in the Superior Court Department on May 16, 2016. Following a jury trial in October 2017 before Judge Peter M. Lauriat, Davis was convicted of armed assault with intent to murder and related firearm offenses. The Appeals Court affirmed the convictions in Commonwealth v. Davis, 97 Mass. App. Ct. 633 (2020). The Supreme Judicial Court granted further appellate review, reversed the convictions, set aside the verdicts, and remanded for a new trial.
Remand instructions
The judgments against Davis are reversed, the verdicts are set aside, and the case is remanded to the Superior Court for a new trial and further proceedings consistent with the opinion.