Court-Tested
eDiscovery Expert
Witness.

An eDiscovery expert witness analyzes how electronically stored information (ESI) was identified, preserved, collected, reviewed, and produced, then offers independent opinions a court can rely on. Typical assignments include assessing collection defensibility, reconstructing a spoliation timeline, validating technology-assisted review (TAR) or predictive-coding results, evaluating proportionality, and writing expert reports and giving testimony built to survive a Daubert / Rule 702 challenge.

Retain the expert as early as possible, ideally before the ESI protocol is negotiated and before any TAR workflow or litigation hold is finalized. The most expensive eDiscovery mistakes — flawed sampling, an inadequate hold, or a stopping criterion chosen after the fact — are baked in at the planning stage. Early involvement also preserves the short forensic-capture window for mobile and ephemeral messaging sources before routine retention cycles overwrite them.

An expert witness is retained by a party to analyze ESI and offer opinions supporting that party's position. A Special Master (or discovery referee) is appointed by the court as a neutral to manage or resolve discovery disputes — overseeing collection, review, and production, and reporting to the judge. Daniel B. Garrie has served in both capacities in 100+ courts and tribunals nationwide and is a JAMS neutral.

Under the amended Federal Rule of Evidence 702, the proponent must show by a preponderance that the opinion reflects a reliable application of reliable methods to the facts. Look for a documented, repeatable methodology rather than a recitation of tools: stated error rates, confidence levels and margins for any sampling, alignment with recognized authority such as The Sedona Conference and EDRM, logged quality controls, and an expert who states the limits of the opinion plainly. Reviewing a prior redacted report and deposition testimony is the best pre-retention check.

Common matters include ESI collection-defensibility analysis, spoliation and sanctions disputes under Rule 37(e) (including ephemeral and mobile messaging such as Signal, Slack, and Teams), proportionality under Rule 26(b)(1), TAR / predictive-coding validation (recall, precision, and elusion testing), and the defensibility of generative-AI-assisted review. Engagements span ESI defensibility, expert reports, and testimony across state and federal courts, arbitrations, and administrative proceedings.

To run a prompt conflict check and scope the work, send the matter name, the jurisdiction or court, the key dates and deadlines, and a brief summary of the ESI issue (for example, a spoliation question, a TAR validation fight, or a collection-defensibility review). That is enough to confirm there is no conflict and to outline an approach and timeline that fits the litigation calendar.

Yes. Daniel B. Garrie has served as an eDiscovery expert witness, discovery referee, and court-appointed Special Master in 100+ state and federal courts, arbitrations, and administrative proceedings across the United States, with more than 20 years in computer forensics and electronic discovery.