Background
Katherine Anne Proctor was convicted by a jury of assault on a minor after her four-month-old daughter, P.P., was brought to a hospital with seizures and lethargy. Medical examination revealed a swollen brain, retinal hemorrhages, rib fractures at various stages of healing, a broken femur, a broken toe, cervical ligament injuries, bruising, abrasions, and a brain contusion — a constellation of injuries that prompted an abuse investigation.
As part of that investigation, police obtained a warrant to search Proctor’s cell phone and extracted virtually all data stored on the device. The extraction revealed text messages between Proctor and her husband, Pinterest activity, and internet searches for a criminal defense attorney made while P.P. was hospitalized. The prosecutor referenced this phone evidence during closing argument to portray Proctor as having a guilty conscience or bad character.
At trial, Proctor moved to suppress the State’s expert testimony, arguing that the diagnostic theory underlying “shaken baby syndrome” is scientifically unreliable. She separately moved to suppress the cell phone evidence as the product of an overbroad warrant. The district court denied both motions, and Proctor appealed her conviction to the Montana Supreme Court.
The Court’s Holding
The Montana Supreme Court affirmed the conviction on all three issues raised on appeal. On the expert testimony, the Court held that P.P.’s case was factually distinguishable from cases relying solely on the shaken baby syndrome triad because the State’s expert diagnosed non-accidental trauma based on a broader constellation of injuries — including rib fractures consistent with gripping an infant’s chest, cervical ligament injuries, and brainstem bruising — rather than the triad alone.
On the warrant, the Court disagreed with the district court and held that the warrant was impermissibly overbroad under both the Fourth Amendment and Article II, § 11 of the Montana Constitution, because its “catch all” language granted law enforcement effectively unfettered access to the entirety of Proctor’s smartphone. The Court nevertheless declined to reverse, concluding that admission of the tainted phone evidence was harmless error in light of the overwhelming cumulative medical evidence of P.P.’s injuries.
On prosecutorial misconduct, the Court found the prosecutor’s closing argument comments regarding Proctor’s character — drawn in part from the unlawfully seized phone data — were “disturbing” and “reprehensible.” Nonetheless, the Court held those statements did not ultimately prejudice Proctor’s right to a fair trial given the strength of the medical evidence and the established timeline placing P.P. exclusively in Proctor’s care before the onset of her injuries.
Key Takeaways
- Expert testimony diagnosing non-accidental or abusive head trauma is admissible where it rests on a constellation of injuries beyond the classic shaken baby syndrome triad, even if the underlying science of shaking mechanics remains contested.
- A cell phone search warrant that authorizes extraction of “all data currently stored” on a device, with expansive catch-all language, is impermissibly overbroad under the Fourth Amendment and the Montana Constitution — but the error can be harmless where independent evidence is sufficiently overwhelming.
- Prosecutorial misconduct during closing argument, even when labeled “disturbing” and “reprehensible” by the court, will not automatically warrant reversal; the defendant must show the misconduct prejudiced the outcome in the context of the full trial record.
- The decision drew a dissent that would have reversed: the dissenters argued the phone evidence was not harmless because the prosecution used it to build a guilt-by-character narrative, and that inviting the jury to infer guilt from Proctor’s search for legal counsel denied her a fair trial.
Why It Matters
This decision reinforces that Montana courts — like courts nationwide — are grappling with how to apply Fourth Amendment particularity requirements to modern smartphones, which contain far more personal data than any object historically subject to search. The majority’s willingness to find the warrant overbroad while still affirming on harmless-error grounds illustrates the high bar defendants face in obtaining reversal based on search-and-seizure violations when independent evidence of guilt is strong. Defense practitioners and prosecutors alike should note that boilerplate “all data” extraction language in cell phone warrants is constitutionally suspect in Montana.
The case also signals ongoing judicial scrutiny of prosecutorial conduct in closing argument, particularly when argument draws on potentially tainted evidence or invites character-based inferences. The sharp disagreement between the majority and the dissent over both the harmlessness of the warrant error and the fairness of the closing argument suggests these questions may be revisited in future cases where the independent evidence is less overwhelming.