Commonwealth v. Cronin

The court’s reasoning

Treating the question as one of first impression, the court surveyed federal decisions and held that testimony is not expert testimony merely because it concerns Cellebrite; the test is whether the particular testimony required specialised knowledge. Connecting the phone, initiating the extraction, and narrowing search parameters in the analysis software was lay perception. Vouching for the tool's reliability was not.

From the opinion

“McLaughlin's claims about Cellebrite's accuracy and reliability — such as its safeguards against data alteration — required specialized, expert knowledge.”

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.

Scope creep

Whether the examiner stayed inside the technical question and out of intent, credibility, and legal conclusions. It is the most avoidable ground on this list and one of the most common.

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.

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.

Practice note

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.