Evidence and testimony
Evidence and testimony in digital marketing disputes

Digital Marketing Expert Witness

I am Bill Hartzer. I have worked in digital marketing since 1996, and I am retained by counsel on both sides to work out what the advertising, analytics and platform records actually show — and, just as often, what they cannot show. 13 channels, 10 kinds of dispute, and 10 guides on how the evidence is found before a retention window closes on it.

Engagement record
Working in digital marketing since
1996
Expert reports
36
Depositions
8
Trials
5
Arbitrations
1
What this work actually is

Most of these disputes turn on data nobody on the file can read


Digital marketing covers the channels a business uses to reach people online — paid search, social, display and programmatic, email, affiliate programs, e-commerce, and the analytics and attribution systems that claim to measure them. When one of those becomes the subject of a dispute, the question is rarely what the strategy should have been. It is what the record shows, who holds it, and how long it will still exist.

A digital marketing expert witness answers that in a form a judge or a jury can follow, and concedes the limits of it before opposing counsel does.

Where it arises

Disciplines

13 channels, each labelled with where the decisive record actually lives — held by the platform, held by the parties, or modeled and therefore not a record at all. Every page names something the evidence cannot settle.

See the disciplines →

What the claim is

Matters

10 kinds of dispute, each labelled with what actually has to be proven: the standard of care, causation, or quantum. Agency and consultant claims, click fraud, false advertising, trademark use in ads, and loss.

See the matters →

Where most matters start

The channels counsel asks about first


Everything on this site →

Before the record is gone

Three things worth settling in the first week


These are written to be useful to counsel who never contacts me. That is deliberate: almost every record in one of these matters sits with a third party on a rolling retention window that no litigation hold can freeze, and the expensive mistake is made before anyone is retained.

By group

The eight groupings everything sits in


Paid Media

4 pages

Where money was spent, and what the record says it bought.

Paid Search Display Paid Social Online Advertising

Organic and Owned

4 pages

Channels a party controls rather than buys, and the records they leave.

Social Media Email Affiliate Content

Commerce and Retail

3 pages

Where the transaction happens, and who holds the transaction record.

E-Commerce Retail Websites

Measurement

2 pages

The systems that claim to say what worked, and what they actually observe.

Analytics Attribution

Performance and Contract

3 pages

What was promised, what was delivered, and what the record shows.

Agency Disputes Scope Disputes Performance Pay

Fraud and Abuse

3 pages

Traffic, clicks and conduct that were not what they appeared to be.

Click Fraud Affiliate Fraud Bot Traffic

Claims and Conduct

2 pages

What was said publicly, to whom, and how it was targeted.

False Advertising Trademark in Ads

Loss and Quantification

2 pages

What the conduct cost, and how that number is built.

Traffic Loss Damages Models

Browse the practice areas →

Keep reading

Tell me what the dispute is about

The parties in general terms, what happened and when, which platforms are involved, and what has already been produced. A conflict check comes first, so send nothing privileged or case-specific in a first message.

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