United States v. Owens

The court’s reasoning

The critical inquiry is whether there is a connection between the data employed and the opinion offered; only an opinion connected to existing data solely by the expert's ipse dixit is properly excluded under Rule 702. The corroborating record here included matching info hashes, a hash match for every one of the 226 pieces of the file, the installed client version, and a most-recently-used folder entry. Both sides' experts agreed that where hash values match, the chance the files differ is astronomically small.

From the opinion

“it is the opinion connected to existing data 'only by the ipse dixit of the expert' that is properly excluded under Rule 702”

Grounds argued

This ruling turned on 2 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.

Ipse dixit

Whether the opinion is connected to the underlying data by anything more than the expert's own assertion. Named for the phrase in General Electric Co. v. Joiner, this is the ground that catches conclusions the report never shows its work for.

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
• HASH VALUE
• IPSE DIXIT

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.

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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.