Challenge the engagement, not the field. Digital forensics comfortably satisfies Rule 702, so attacks on the discipline fail. What succeeds is narrower: unverified acquisitions, gaps in chain of custody, a method that cannot be reproduced from the report, or an opinion that reaches past what the artifacts support.
Start by reading for what is missing
A forensic report should let another examiner repeat the work. Before drafting anything, check whether it states:
- the tools and versions used;
- the acquisition method, and whether the image was hash-verified against the source;
- an unbroken account of handling — see chain of custody;
- the specific artifacts each conclusion rests on;
- what the analysis cannot establish.
An omission in any of these is more productive than an argument about interpretation, because it is objective and the expert cannot talk their way past it in a deposition.
The five attacks that actually land
Verification. Was a hash value recorded at acquisition and confirmed before analysis? Without it, the expert cannot demonstrate that what they examined is what was seized. This is binary and checkable against the acquisition log.
Custody gaps. A period nobody can account for. You do not need to allege tampering — you need the expert to concede they cannot exclude it.
Reproducibility. If the report states conclusions without the steps, ask in deposition how a second examiner would verify them. Under the amended Rule 702 this is a gatekeeping question, not merely a matter of weight.
Fit. A computer forensics examiner opining on mobile artifacts, or an analysis that is technically sound but does not address the question actually in dispute.
Overreach. The most common and most rewarding. Artifacts can show that files were copied to a USB device at a particular time. They cannot show intent, knowledge, or what the person planned to do with them. An expert who testifies to a state of mind has stepped outside their expertise and handed you the cross-examination.
Retain your own examiner early
Not necessarily to produce a competing report — often the more valuable work is a technical read of the other side's report to tell you which threads are real. Counsel reading a forensic report alone will identify the arguable conclusions; an examiner will identify the missing verification step, the tool used outside its validated scope, or the artifact that means something other than what the report says.
That work is comparatively cheap and it determines whether a motion is worth filing at all.
Consider whether a motion is the right instrument
A Daubert motion that fails can leave the expert looking tested and credible. Where the flaws go to weight rather than admissibility — an incomplete analysis, an alternative explanation not excluded — cross-examination in front of the fact-finder is frequently more effective than a pretrial motion the court denies.
And where the underlying facts are genuinely contested rather than the methodology, proposing a forensic neutral to examine under an agreed protocol can resolve in weeks what duelling reports would litigate for a year.
From our work
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