Expert Report on Class Damages

Produces a court-ready expert damages report demonstrating class-wide measurability of harm under a common methodology, structured to survive Daubert challenge and support FRCP 23(b)(3) certification.

Prerequisites

Class definition and complaint — allegations, liability theories, relief sought
Engagement scope — retention letter specifying opinions requested and exclusions
Damages evidence — transaction records, financial statements, pricing data, surveys, or defendant-produced databases
Expert CV — credentials, publications, prior testimony history
Opposing expert reports (if any) — to distinguish competing methodologies
Legal authorities — jurisdiction's Daubert/Frye standard; prior rulings on proposed methodology

Quick Start

Gather prerequisites above
Confirm jurisdiction's admissibility standard (Daubert, Frye, or Sargon)
Select primary damages methodology from the methodology table below
Walk through each output section in order
Run the compliance checklist before finalizing

Output Sections

1. Title Page

| Field | Content | |---|---| | Court & case caption | Full court name, case number, parties | | Expert identity | Name, title, firm/institution | | Retaining party | Plaintiff / Defendant / Neutral | | Report date | Date of signing | | Confidentiality designation | Per applicable protective order |

2. Introduction & Engagement Scope

Identify the putative class, claims, and relief sought
State questions addressed:
- Can damages be measured class-wide using common evidence?
- What is the aggregate class-wide damages amount?
- Do individual damages issues predominate over common ones?
Explicitly state what is not in scope (liability, causation, individual allocation) to limit deposition exposure

3. Expert Qualifications

Tie credentials directly to the methodology used — generic backgrounds invite Daubert attack.

| Category | Detail | |---|---| | Education | Degree, institution, year | | Relevant experience | Industry, sector, years | | Publications | Those bearing on methodology or damages field | | Prior testimony | Number of matters, courts, subject areas | | Specific expertise | Why qualified for this methodology |

4. Methodology & Economic Framework

Select and justify the primary methodology:

| Methodology | Best For | Key Requirements | |---|---|---| | Regression analysis | Price-fixing, overcharge | Sufficient transaction data; control variables | | Before-and-after | Market disruption, fraud | Clean pre-period baseline; comparable windows | | Yardstick / benchmark | Product liability, consumer harm | Comparable unaffected market or product | | Lost profits (but-for) | Breach, interference | Reliable projections; defensible counterfactual |

Must include:

Cite academic literature and FJC Reference Manual on Scientific Evidence (3d ed.)
Address prior court acceptance in similar cases
Explain why rejected alternatives are less reliable
Demonstrate common proof: damages calculable without individualized inquiries

5. Data Sources & Assumptions

For each data source, document:

| Element | Description | |---|---| | Origin | Who produced it, how obtained | | Processing | Cleaning, normalization, exclusions | | Reliability | Suitability for analysis; completeness concerns | | Limitations | Known gaps; defendant data issues |

Material assumptions: state each explicitly, cite supporting basis, and perform sensitivity analysis showing damages remain robust across reasonable variations.

6. Damages Analysis & Calculations

Present step-by-step:

Class size — method for identifying affected members
Per-member harm — average injury and distribution across subgroups
Aggregate damages — formula, inputs, result

For each step: show formula, data inputs with source citations, and output value.

Use tables/charts for judge/jury accessibility
Calculate each measure separately (compensatory, restitutionary, disgorgement) — explain overlaps to avoid double-counting
Address mitigation, offsets, or benefits reducing net damages
Present sensitivity ranges for uncertain point estimates

7. Conclusions

State aggregate damages with confidence level
If range: identify variation drivers
Tie each conclusion to methodology and data
Acknowledge modeling uncertainties — avoid false precision
Confirm damages provable to reasonable certainty under applicable standard

8. Appendices

| Appendix | Contents | |---|---| | A | Expert CV | | B | Materials considered (complete list) | | C | Calculation workpapers | | D | Data tables and source extracts | | E | Demonstrative exhibits | | F | Bibliography | | G | Model/software documentation (if proprietary tools) |

Compliance Checklist

[ ] Daubert: methodology is testable, peer-reviewed where possible, has known error rate, and is generally accepted — address all four factors [VERIFY circuit's Daubert formulation]
[ ] FRCP 23(b)(3): common questions predominate; model does not require individualized mini-trials
[ ] FRE 702: opinions based on sufficient facts, reliable methodology, reliably applied to facts
[ ] Scope discipline: no opinions beyond engagement scope
[ ] Data provenance: chain of custody documented for all data relied upon
[ ] Replication: methodology sufficiently documented for opposing expert to replicate
[ ] Jurisdiction: confirm controlling admissibility standard — Daubert, Frye, Sargon (CA), or other [VERIFY by jurisdiction]