An SEO damages expert establishes two things in litigation: whether a party’s conduct caused a website to lose organic search traffic or visibility, and how much traffic was lost compared with what the site would have earned otherwise. I am Bill Hartzer, and I do that work as an SEO expert witness, in expert reports, rebuttal reports, deposition and trial testimony, for plaintiffs and for defendants.
Just as important is what an SEO damages expert should not do. I opine on causation and on the lost traffic. I do not convert that traffic into a dollar figure. Revenue per visit, margin, mitigation and present value belong to an economist or accountant, who takes my traffic analysis as a stated input. An expert who calculates the money alongside the traffic invites an attack on the financial half of the opinion that can take the technical half down with it.
The disputes where SEO damages are claimed
Lost search traffic is claimed in a wide range of matters. The ones I see most often:
- Agency and contractor disputes, where a client claims an SEO provider’s work caused rankings to fall or failed to meet the standard of care.
- Website and domain migrations, where a redesign, platform change or domain change lost rankings that had taken years to build.
- Negative SEO and sabotage, where a competitor or former vendor is accused of spam links, content scraping, false removal requests or hacking.
- Trademark and unfair competition, where a competitor’s use of a brand name in content, domains or ads is alleged to have diverted search traffic.
- Defamation and reputation matters, where the question is how visible a defamatory page was in search results and for how long.
- Domain theft and hijacking, where control of a domain, its DNS or its redirects was lost for a period.
Each of these turns on the same core question: what would the site’s organic traffic have been without the conduct, and what was it instead?
The data a lost traffic analysis is built on
Damages opinions are only as strong as the data under them, and after the December 2023 amendment to Federal Rule of Evidence 702, insufficient data is an admissibility problem rather than a question of weight. I build from first-party sources wherever they exist:
- Google Search Console performance data: clicks, impressions and positions by query and page. Google keeps roughly sixteen months on a rolling basis, so it must be exported early.
- Google Analytics 4 (GA4) or other analytics data, including other channels such as direct, email and paid traffic, which serve as controls.
- Raw server and CDN logs, which show what search engine crawlers actually requested and when.
- Crawls of the site and archive captures that reconstruct what changed and on what date.
- Change records: deployment logs, CMS revision history, robots.txt and redirect changes, and disavow file versions.
Third-party estimates from tools such as Semrush, Ahrefs and Similarweb are modeled numbers drawn from proprietary panels. They are useful for orientation and for competitor comparisons. They are a weak foundation for a damages opinion when the party’s own Search Console and analytics data exists and was not used, and I say so whenever I rely on one.
How I establish that the conduct caused the loss
A before-and-after comparison of organic sessions attributes to the defendant everything that Google, the calendar and the market did during the same period. Google ships several core updates a year plus continuous unannounced changes, search demand moves with the season and the economy, and competitors act independently. Timing alone does not establish causation.
Search data does offer unusually good internal controls, and a defensible causation analysis uses them:
- The site’s other traffic channels, as a control for changes in demand that have nothing to do with search.
- Unaffected pages or sections of the same site, as a control for sitewide algorithm events.
- Competitor visibility over the same period, as a market-level control.
- Query-level demand data, so a collapse in searches is not mistaken for a collapse in rankings.
- The calendar of Google core updates and known search changes, so each one can be tested as an alternative cause.
Combining affected and unaffected groups across the event date in a difference-in-differences comparison is a real method with a measurable error rate. It is the kind of analysis a court applying Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999), expects from a technical expert, and it survives cross-examination in a way a single overlaid line chart does not.
Measuring how much traffic was lost
Once causation is established, the loss itself is measured against a counterfactual: a reasoned estimate of the traffic the site would have earned had the conduct not occurred. The analysis I deliver to the economist states:
- The baseline period and why it was chosen.
- The counterfactual and how it was built, including the controls above.
- The lost clicks or sessions by month, separated into branded and non-branded search where that distinction matters.
- The recovery period, and the point at which any remaining loss can no longer be attributed to the conduct.
- The range of reasonable estimates, not only a single figure.
The economist then applies conversion rates, order values or lead values, margins, mitigation and discounting. Each opinion stands on its own, and each relies on the other only through a clearly stated assumption.
Why older damages models need revisiting
Damages models built before 2024 generally assumed that the relationship between rankings and traffic was stable. It is not. AI Overviews now appear on a large share of Google searches, and a growing share of searches end without a click to any website. A model comparing 2023 traffic with 2025 or 2026 traffic that does not control for that change attributes an industry-wide shift to the defendant.
That cuts both ways. It is a serious weakness for a plaintiff’s expert who ignores it, and a strong confound for a defendant to raise. The ability to measure the effect on the specific keywords and pages at issue, rather than describe it in general terms, is now one of the most valuable capabilities in this field.
Where SEO damages models fail
When I am retained to rebut another expert’s damages opinion, the faults tend to repeat:
- Rank-tracker positions or tool traffic estimates used as if they were measured traffic.
- A before-and-after comparison with no control for core updates, seasonality or demand.
- A growth curve projected forward that could produce almost any figure the analyst wanted.
- Branded traffic, which the conduct may not have affected, counted as lost.
- Paid search and organic search counted together, or a recovery in paid traffic ignored.
- No recovery period, so a temporary loss is extended indefinitely.
- The SEO expert performing the economic calculation without the qualifications or method to do it.
Courts have excluded damages models for ignoring known market conditions, for projections capable of producing any desired result, and for resting on assertion rather than analysis. Each fault in the list above is a route to one of those outcomes.
Preserve the evidence first
The best evidence in a search damages case expires on a schedule. Search Console data rolls off after about sixteen months, GA4 purges event-level data on its retention setting, server logs are commonly rotated within 30 to 90 days, and a redesign overwrites the site itself. A preservation letter that names these sources, sent before anyone argues about the merits, is the most valuable step counsel can take. The full preservation checklist is on the SEO expert witness page.
Related expert testimony
Reports, deposition and trial testimony, including the cross-examination questions an SEO expert should expect, are covered on the SEO expert testimony page. Analytics evidence is covered on the web analytics expert witness page, paid search disputes on the Google Ads expert witness page, and domain disputes on the domain name expert witness page.
Frequently asked questions
What does an SEO damages expert do?
An SEO damages expert determines whether specific conduct caused a website to lose organic search traffic or visibility, and measures how much was lost compared with a reasoned estimate of what the site would otherwise have earned. The expert supports that opinion with first-party data and a reproducible method, and defends it in deposition and at trial.
How is lost organic traffic calculated?
Lost organic traffic is calculated as the difference between a counterfactual, the traffic the site would have earned without the conduct, and the traffic it actually earned. A reliable counterfactual controls for algorithm updates, seasonality, search demand and competitor movement, usually by comparing affected and unaffected pages or channels across the event date.
Can an SEO expert testify to dollar damages?
An SEO expert should testify to the traffic and visibility loss. Converting that loss into dollars requires revenue, margin, mitigation and present value analysis that is normally performed by an economist or accountant, who uses the SEO expert’s traffic figures as an input.
What data is needed to prove SEO damages?
The strongest damages opinions rest on the website owner’s own Google Search Console data, analytics data, server logs and change records, supported by crawls and archive captures. Third-party tool estimates can help with orientation and competitor comparisons but are a weak primary foundation when first-party data exists.
Do Google algorithm updates affect damages claims?
Yes. Google releases several core updates each year, and any of them can move rankings independently of the conduct at issue. A damages analysis has to test each update during the relevant period as an alternative cause, or opposing counsel will.
How do I engage you on a damages matter?
The first call is a conflict check and a short conversation about what the dispute turns on, at no charge. Engagements usually begin on a consulting basis, so the data can be examined before anyone commits to a testifying designation. Call 214-236-4378 or use the contact page.
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