Which court cases have addressed admissibility of browser fingerprinting evidence in criminal prosecutions?
Executive summary
There are robust bodies of case law addressing the admissibility of traditional friction‑ridge fingerprint evidence stretching back more than a century (People v. Jennings) and a large modern literature finding courts ordinarily admit such evidence (multiple federal and state opinions), but the materials provided contain no reported criminal decisions specifically addressing the admissibility of browser or “digital” browser‑fingerprinting evidence in prosecutions (limitation of reporting) [1] [2] [3].
1. The historical pedigree: Jennings and a century of admissibility
The American court system began grappling with fingerprint evidence in the early 1900s, most famously in People v. Jennings, which the Illinois Supreme Court upheld and which scholars mark as the first sustained judicial treatment of fingerprint admissibility in the United States [1]; from that era forward courts regularly treated properly obtained fingerprint comparisons as admissible evidence [4] [1].
2. Modern federal gatekeeping: Daubert, Llera Plaza, Mitchell and the status quo
After the Supreme Court’s Daubert decision, judges were asked to scrutinize forensic methods more closely, and notable federal rulings tested fingerprint science—Judge Louis Pollak’s initial skepticism in United States v. Llera Plaza drew attention, but subsequent handling and government responses preserved the prevailing trend of admission; comprehensive reviews find that federal and state courts have overwhelmingly admitted fingerprint evidence under Daubert-style gatekeeping [3] [5] [2].
3. Empirical reviews: courts admit most fingerprint evidence but exclude problematic applications
A systematic review of more than 315 written state and federal opinions since Daubert concludes that most courts admit fingerprint testimony and that only one court in the United States has broadly excluded fingerprint evidence as an unreliable method; courts more commonly exclude particular examiners or limit testimony when application, qualifications, or overstated claims (e.g., “zero error rate”) are at issue (Brandon Garrett’s review) [2] [6].
4. State court wrinkles and emerging skepticism
Some state appellate decisions and trial rulings have begun to identify reliability problems in latent fingerprinting—North Carolina v. McPhaul is singled out as a 2017 decision that flagged systemic concerns applicable across forensic disciplines—illustrating that while admission is common, judicial scrutiny and criticism have increased in recent years [3].
5. Digital evidence analogies: courts have admitted enhanced digital comparisons but not browser fingerprints (in these sources)
Courts have admitted a range of digital‑forensic evidence—audio enhancement, video enhancement, and other digitally assisted comparisons—when foundations as to accuracy, authenticity, and trustworthiness were laid (United States v. Calderin‑Rodriguez is cited as an example admitting digitally enhanced materials) [7]. However, the collected reporting and scholarship reviewed here do not identify any reported criminal case where courts squarely addressed the admissibility of browser fingerprinting (that is, passive device/browser‑configuration fingerprint profiles used to link online activity to a device or account), so no definitive statement about judicial treatment of browser fingerprints can be drawn from these sources (limitation of reporting) [7] [2].
6. Why the gap matters and what to look for next
Browser fingerprinting raises distinct questions—statistical reliability, population uniqueness, stability over time, and the expert’s ability to explain methods to a trier of fact—that differ from traditional friction‑ridge issues, and the existing fingerprint literature suggests courts will focus less on label (“fingerprint”) and more on method, validation, and expert application when a case emerges; the sources recommend deeper empirical research and judicial education about forensic limitations, a theme repeated in scholarship calling for essential research to evaluate forensic practices [6] [8].
7. Bottom line for prosecutors, defenders, and researchers
The body of case law for physical fingerprint comparisons is large and largely permissive, with notable pockets of skepticism and limits on particular experts or claims [2] [3]; by contrast, within the set of documents provided there are no reported criminal rulings specifically admitting or excluding browser‑fingerprinting evidence, so anyone seeking precedents on that precise technique must consult databases for more recent cases or targeted digital‑forensics reporting beyond these sources (limitation of reporting) [2] [7].