expert-witness-impeachment

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

1. Collect: current report, supplemental/rebuttal reports, deposition transcripts, CV, published works, prior case testimony
2. Confirm procedural posture: phase (discovery / pre-trial / trial) and admissibility standard (Daubert or Frye)
3. Run analysis across all five dimensions below
4. 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