| name | expert-witness-impeachment |
| title | Expert Witness Impeachment Analysis |
| description | Analyzes expert witness materials (reports, depositions, CVs, publications) to identify inconsistencies, opinion drift, and methodological failures for impeachment. Produces a prioritized inconsistency register, cross-examination questions, and Daubert/Frye challenge assessment. Use when challenging expert reliability or credibility during discovery, pre-trial, or trial in commercial litigation. |
| author | CaseMark |
| author_url | https://github.com/CaseMark/skills/tree/main/skills/legal/expert-witness-impeachment |
| license | Apache-2.0 |
| version | 0.1.0 |
| execution_mode | open |
| jurisdiction | us |
| practice | litigation |
| language | en |
| tags | ["analysis"] |
Expert Witness Impeachment Analysis
Systematically compares expert materials to surface contradictions and methodological failures that support cross-examination, exclusion motions, or weight challenges.
Quick Start
- Collect: current report, supplemental/rebuttal reports, deposition transcripts, CV, published works, prior case testimony
- Confirm procedural posture: phase (discovery / pre-trial / trial) and admissibility standard (Daubert or Frye)
- Run analysis across all five dimensions below
- Produce outputs in order: Register → Patterns → Cross-Exam → Admissibility → Motion Summary
Analysis Dimensions
| Category | What to Find |
|---|
| Opinion Changes | Modified, reversed, or newly qualified conclusions across documents |
| Methodological Inconsistencies | Different approaches, data sets, or protocols without explanation |
| Factual Contradictions | Inconsistent statements about underlying facts or reviewed evidence |
| Credential Discrepancies | Qualifications or publications stated differently across documents |
| Unsupported Conclusions | Testimony exceeding the report's scope or lacking methodological basis |
Output Structure
1. Inconsistency Register
For each finding:
- ID: sequential number
- Category: from table above
- Materiality: High / Medium / Low (effect on ultimate opinion)
- Source A: [document, page, line] — verbatim quote
- Source B: [document, page, line] — verbatim quote
- Delta: one-sentence contradiction description
- Expert explanation offered: yes/no (summarize if yes)
2. Pattern Assessment
- Group related inconsistencies to distinguish systemic unreliability from isolated error
- Flag temporal patterns: opinions strengthening/weakening without new data, or shifting after opposing challenges
- Separate bias indicators from legitimate opinion evolution
3. Cross-Examination Blueprint
For each High/Medium finding:
- 2–4 sequenced questions using the expert's own words
