Philadelphia Criminal Defense Lawyer Zak T. Goldstein, Esquire

The Pennsylvania Supreme Court has decided Commonwealth v. Foster, No. 12 WAP 2024 (Pa. May 19, 2026), holding that the totality of the circumstances supported reasonable suspicion to detain the defendant after a ShotSpotter alert reported gunfire on a residential block at 2:00 a.m. The Court declined to address whether ShotSpotter alerts, standing alone, are reliable enough to support a Terry stop, treating the alert here as one factor among several.

There is also a meaningful win for the defense bar tucked inside the opinion. The Court refused to credit the Commonwealth’s “high-crime area” argument because the officer’s testimony was too vague and was not tied to the time of the stop. That portion of the decision reinforces last year’s ruling in Commonwealth v. Lewis, 343 A.3d 1016 (Pa. 2025), and gives defense counsel a usable tool at suppression hearings.

The Facts

At around 2:00 a.m. on September 17, 2019, a Pittsburgh police officer received a ShotSpotter alert reporting a single gunshot near 1439 Hoffman Street. A second alert reported four more shots at the same location while the officer was en route. He reached the intersection of Hoffman and Chateau Streets about ten to fifteen seconds after the second alert and saw a parked car with its headlights on. The defendant was in the driver’s seat. A woman was in the passenger seat. They were the only people on the street.

As the officer turned onto Hoffman Street and activated his overhead lights, the defendant got out of the car and walked toward a nearby residence. The officer testified that the female appeared to be “moving around in the car trying to grab things,” including her purse. The officer exited his cruiser and ordered the defendant to return to the street. When he did not comply, officers drew their weapons and forcibly handcuffed him.

After the seizure, officers recovered shell casings near the car and a firearm in the woman’s purse. The woman later admitted she had accidentally discharged the weapon inside the vehicle. The defendant meanwhile, smelled of alcohol and his eyes were glassy. He failed field sobriety testing, and his BAC came back at .200. He was charged with DUI and with driving while his operating privilege was suspended.

The defendant filed a motion to suppress, arguing that the seizure was not supported by reasonable suspicion. The trial court denied the motion, the defendant was convicted at a bench trial, and the Superior Court affirmed in an unpublished memorandum. The Supreme Court granted allocatur to address whether the lower courts placed too much weight on the defendant’s spatial and temporal proximity to the ShotSpotter alerts.

The Legal Framework

Article I, Section 8 of the Pennsylvania Constitution and the Fourth Amendment both prohibit unreasonable seizures. An investigative detention (a Terry stop) must be supported by reasonable suspicion of criminal activity. Reasonable suspicion is less demanding than probable cause but still requires “specific and articulable facts” supplying a “particularized and objective basis for suspecting the particular person stopped of criminal activity.” The stop must be “justified at its inception,” and facts that develop only after the seizure cannot retroactively support it.

The parties agreed that the seizure occurred when the officer exited his cruiser and ordered the defendant back to the street. The question was whether the totality of the circumstances at that moment supplied reasonable suspicion.

The Supreme Court’s Holding

The Court held that the totality of the circumstances supported reasonable suspicion. It identified four factors: (1) two ShotSpotter alerts indicating gunfire in a residential neighborhood in the middle of the night; (2) the officer’s rapid response, which left limited opportunity for a shooter to flee the immediate area; (3) the fact that the defendant and the woman were the only people present at the precise location of the alerts; and (4) what the Court characterized as the pair’s “furtive and evasive behaviors” when the officer arrived — the woman moving around inside the car as the cruiser approached with overhead lights activated, and the defendant getting out of the car and walking toward a private residence as the officer pulled up.

The Court declined to treat ShotSpotter alerts as the equivalent of anonymous tips. The defendant and amici — the ACLU, the Pennsylvania Innocence Project and PACDL, and the Allegheny County Public Defender’s Office — had urged the Court to adopt that framework and require independent corroboration of the alert before it could be used to justify a stop. The Court called the proposed framework one that would “unnecessarily complicate[ ] the straightforward legal issue presented,” and resolved the case on a totality-of-the-circumstances basis instead. Importantly, the Court did not actually decide whether ShotSpotter is reliable. It described the technology’s reliability as not properly preserved and ultimately immaterial on the record before it.

The High-Crime Area Argument Fails

The most useful part of the opinion for defense practitioners is the Court’s rejection of the Commonwealth’s “high-crime area” argument. The entirety of the proof was an officer’s answer to a leading question: asked whether the area was “known as a high-crime area,” he replied, “Manchester has its hot spots, yes,” and confirmed that the location “has been” a hot spot “in the past.”

Citing Lewis, the Court reiterated that “merely intoning buzzwords is never sufficient to prove an area is high in crime,” and that conclusory testimony characterizing an area “in broad generalities” does not establish the factor. The Commonwealth must also tie the testimony to the time of the stop, not to some unspecified moment “in the past.” The Court accordingly removed the high-crime area factor from the analysis.

Although the use of ShotSpotter as a factor is bad for the defense, the high crime analysis is helpful. The high crime area label has been doing a lot of heavy lifting in Terry stop cases for years, often supported by nothing more than an officer reciting the magic words on direct. After Lewis and now Foster, that testimony has to come with specifics: what kind of crime, how the officer knows, and a nexus to the time and place of the stop, or it does not count at all.

The Takeaway

Foster expands the set of circumstances in which a ShotSpotter alert can be used to justify an investigative detention in Pennsylvania. The Court did not hold that a ShotSpotter alert alone supports reasonable suspicion, and it expressly declined to decide whether ShotSpotter alerts are reliable enough to be treated like other evidence of crime. But it did hold that an alert, combined with the defendant’s presence at the reported location moments after the alert, the absence of any other people on the scene, and what the Court characterized as furtive and evasive behavior, is enough.

At the same time, the decision continues the Court’s push, begun in Lewis, to require more than buzzwords before an area can be treated as a high-crime area in the reasonable-suspicion analysis. A one-line answer from an officer that the location has been a “hot spot” in the past is no longer sufficient on its own.

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PA Supreme Court: ShotSpotter Alert Plus Furtive Movements and Walking Away Provides Reasonable Suspicion