State v. Pratt

The court’s reasoning

The court applied Vermont Rule 702's liberal thrust and Kumho's flexible, non-mechanical inquiry to non-scientific technical testimony, surveying decisions from other jurisdictions. It concluded that an investigator must have specialised knowledge in using the particular software or device but need not understand its internal programming. The examiner's 800-plus hours of forensic training, a week of dedicated Cellebrite training, and use of the tool on hundreds of phones since 2010 supplied the reliability foundation.

From the opinion

“it is not required — nor is it practical — for an investigator to have expertise in or knowledge about the underlying programming, mathematical formulas, or other innerworkings of the software”

Grounds argued

This ruling turned on 3 of the eight arguments that recur across the docket. Each is defined the same way on every entry, so the same ground can be followed across rulings that reached opposite results.

Tool reliability

Whether the software or hardware used — an imaging tool, a carving engine, an extraction platform — produces accurate results, and whether the examiner can say how that is known. Courts rarely require a tool to be validated from first principles, but they do expect the examiner to know its limits.

Qualifications

Whether this witness — by training, certification, or documented casework — is competent to give this opinion. Courts routinely admit examiners qualified by experience alone, and routinely narrow them when the opinion strays past the experience they described.

Methodology

Whether the steps the examiner took are a recognised way of answering the question asked, and whether they were followed as described. Most digital-forensics rulings turn on this rather than on anything the field would call science.

Practice note

Terms used on this page

Every term below is defined in the forensic glossary — what it is, why a case turns on it, and what happens in the matter when it is mishandled.

• FRE 702
• KUMHO TIRE

Rulings on the same grounds

One ruling is not a rule. These are the other entries in the docket argued on the same grounds, most-cited first — including the ones that came out the other way, which are the ones worth reading before relying on this entry for anything.

• The Daubert Docket

  All 55 rulings, filterable by ground, outcome and court, with the distribution across the three outcomes reported up front.

• Daubert and digital evidence

  The argument this docket is the evidence for: why an opinion stated one level too strongly is an admissibility problem under Rule 702(d).

• Daubert Exposure Check

  Twelve questions about an expert's methodology, mapped to the failure modes these rulings keep finding, with the remediation for each gap.

• Daubert or Frye?

  Which reliability test your forum applies — settle that before relying on a ruling from another jurisdiction.

← BACK TO THE DAUBERT DOCKET

Attorney advertising / expert services. Each entry summarises a decision as it appeared in the opinion linked from that entry, on the day the entry was written. Decisions are reversed, vacated, superseded, and distinguished, and the text of Federal Rule of Evidence 702 was itself amended effective 1 December 2023 — check the current status and subsequent history of any ruling before relying on it. Nothing here is legal advice, none of it is a prediction about how any court will rule, and it is not a substitute for the rules, standing orders and case law of your own forum.