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SCOW addresses use of ShotSpotter alert in assessing reasonableness of Terry stop

State v. Avan Rondell Nimmer, 2022 WI 47, June 23, 2022, reversing an unpublished court of appeals decision; case activity (including briefs)

This decision ultimately involves only the application of well-settled 4th Amendment law to the particular facts of the case rather than development of the law. But it comes perilously close to something worse, for three justices embrace a modification of the quantum of evidence needed to justify an investigatory stop and accept uncritically the claims that the manufacturer of ShotSpotter acoustic sensors makes for the accuracy of its product and touts the device’s asserted accuracy in assessing reasonable suspicion in future cases.

The issue in this case is whether police had reasonable suspicion to stop and frisk Nimmer after they found him near an area to which they were dispatched after a ShotSpotter alert. (For the uninitiated, ShotSpotter is an acoustic sensor that purports to be able to identify gunshots as opposed to, say, fireworks or backfiring car engines. (¶4).) The court of appeals concluded the totality of the circumstances didn’t support the stop and frisk. (¶¶2, 17-19). The supreme court unanimously agrees that’s the court of appeals was wrong on that score. (¶¶3, 61, 69, 74). Because the decisions is a fact-dependent application of the existing standard for a stop, we refer the reader to the decision (¶¶6-12, 63) for a description of the circumstances of the stop.

So why review a case involving the application of a long-established standard to the facts of Nimmer’s case? Apparently because in petitioning for review, the state argued that ShotSpotter alerts are a “technological” rather than a “citizen” tip and therefore more accurate and reliable, impliedly worthy of more weight in the totality-of-the-circumstances calculus. In support of this proposition the state cited a law student note that relies on ShotSpotter’s self-interested advertising claims and some mainstream media news articles.

As it happens, the proposition that a ShotSpotter alert is some sort of specially important fact supporting reasonable suspicion doesn’t determine Nimmer’s case. Four of the justices conclude the stop of Nimmer was justified based on the usual totality-of-the-circumstances analysis of all the facts the police had at the time they detained Nimmer. That naturally includes the ShotSpotter alert, though as one concurrence emphasized (Dallett, joined by A.W. Bradley and Karofsky), the alert didn’t get any special weight. (¶¶64-69). However, three justices (R.G. Bradley, Ziegler, Roggensack) go beyond the usual Terry stop analysis by relying on two troubling additional rationales for reversing the court of appeals:

  • First, the three justices contend that “the gravity of the crime being investigated” is relevant to the determination of reasonable suspicion—indeed, that the graver the suspected criminal conduct, the lower the quantum of suspicion needed to stop and frisk, a sort of “sliding scale” approach to reasonable suspicion adopted by other courts, e.g.United States v. Rickmon, 952 F.3d 881–82, 884 (7th Cir. 2020), cert. denied, 141 S. Ct. 2505 (2021); United States v. Burgess, 759 F.3d 708, 710–11 (7th Cir. 2014); United States v. Goodwin, 449 F.3d 766, 769 (7th Cir. 2006). (¶¶28, 39-58). Investigations of suspected shootings, especially in a residential area, are particularly grave, of course, so police should be able to act with less information.
  • Second, they accept the claims that ShotSpotter is a powerful and reliable tool, comparable to the investigating officer hearing the shot, which means the police in this case were right to conclude they were responding to investigate a shooting and thus making the quantum of suspicion needed lower (see point one, above). (¶¶29 n.12, 44).

Only three justices embraced the “sliding scale” doctrine and accepted the reliability and accuracy of ShotSpotter, so neither of these rationales are majority holdings that bind the lower courts. As one concurring justice (Hagedorn) observes, “portions of the court’s opinion go farther than necessary. In particular, the opinion suggests—for what appears to be the first time in the Wisconsin reports—that the quantum of suspicion necessary to conduct an investigatory stop is lower for the type of criminal investigation that occurred here. I do not believe this issue was developed in a sufficiently meaningful way for me to opine on it, and resolving it is unnecessary to decide this case.” (¶74). Thus, as the other concurrence notes, the lead opinion should not be read “too broadly.” (¶¶61 & n.1, 70).

Note that the defense acquiesced in the claims of ShotSpotter’s accuracy and reliability, leaving the field open for a court to accept the claims. (¶¶5, 65 n.5). This lack of skepticism is far from universal. For more searching and critical opinions, see Mitchell L. Doucette, et al., Impact of ShotSpotter Technology on Firearm Homicides and Arrests Among Large Metropolitan Counties: a Longitudinal Analysis, 1999-2016, 98 J. Urban Health 609 (2021); City of Chicago Office of Inspector General, The Chicago Police Department’s Use of ShotSpotter Technology (August 2021); an amicus brief submitted by Northwestern University Law School’s MacArthur Justice Center in support of a defendant’s challenge to the reliability of ShotSpotter and the use of evidence of a ShotSpotter alert in court; this news report on challenges to ShotSpotter, which includes a link to a motion challenging the admission of evidence in a case that was eventually dismissed; and this ACLU page. A couple of recent law review articles might also be of interest: Benjamin Goodman, ShotSpotter—The New Tool to Degrade What is Left of the Fourth Amendment, 54 UIC L. Rev. 797 (2021), and Harvey Gee, Bang!”: ShotSpotter Gunshot Detection Technology, Predictive Policing, and Measuring Terry‘s Reach, 55 U. Mich. J. L. Reform 767 (2022). Thus, if you have a case where ShotSpotter played a role in the stop of your client, don’t concede the accuracy of the technology; rather, challenge it, and argue it shouldn’t figure in the reasonable-suspicion calculus at all. Dallett’s concurrence also lays out some arguments about the limits of ShotSpotter itself and of its significance in a particular case, even if it is accurate. (¶¶65-67).

As for the “sliding scale” doctrine, the fact it was advanced by only three justices and rejected by the other four means it’s not the law in Wisconsin, so no circuit court or court of appeals panel should be using it.

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