Overview of Expert Witness Services
Bill Hartzer provides expert witness services for legal matters involving digital marketing. His work covers the full range of digital channels, including paid search, search engine optimization, social media, display advertising, email marketing, affiliate programs, and the analytics and attribution systems that measure their performance.
Each engagement is tailored to the specific needs of the case. Services may include an initial consultation, a full expert report, a rebuttal report, deposition testimony, trial testimony, or a combination of these, depending on the stage and requirements of the litigation.
Core Service Areas
Case Evaluation and Early-Stage Consulting
Many engagements begin with an initial consultation to assess whether digital marketing issues are central to the dispute and whether expert involvement is warranted. During this phase, Bill reviews the key allegations, evaluates the available data, and provides counsel with a preliminary assessment of the digital marketing questions at issue.
Early-stage consulting can also include guidance on data preservation, identification of relevant digital marketing evidence, and recommendations for discovery requests related to marketing platforms, analytics systems, and campaign records.
Expert Reports
Expert reports are the foundation of most digital marketing expert witness engagements. Bill prepares detailed, written reports that analyze the digital marketing evidence, present findings, describe the methodology used, and state conclusions that are defensible under cross-examination.
Expert reports in digital marketing cases typically include analysis of one or more of the following:
- Historical paid search campaign performance, spend, and return on investment
- Organic search traffic patterns, ranking changes, and search visibility trends
- Social media advertising campaigns and organic social performance
- Analytics data, including traffic sources, conversion tracking, and attribution models
- Website technical configurations, migrations, and their effects on marketing performance
- Click fraud, invalid traffic, and ad placement compliance
- Industry standards of care and best practices for digital marketing management
- Causation analysis connecting specific actions or failures to measurable business impact
- Damages quantification based on lost traffic, leads, conversions, or revenue
Rebuttal Reports
When the opposing side has retained a digital marketing expert, Bill prepares rebuttal reports that examine the opposing expert's methodology, challenge unsupported conclusions, identify errors in data analysis, and present alternative interpretations where the evidence supports them.
Effective rebuttal requires both technical depth and the ability to clearly articulate where and why the opposing expert's analysis is flawed. Bill's hands-on experience with the platforms and data sources at issue enables him to identify methodological weaknesses that a less experienced reviewer might miss.
Depositions and Trial Testimony
Bill is available for deposition and trial testimony. His approach to testimony emphasizes clarity: explaining technical digital marketing concepts in straightforward language that helps judges and juries understand the evidence without oversimplifying the analysis.
Effective expert testimony requires more than technical knowledge. It requires the ability to organize complex information, anticipate cross-examination challenges, and present findings in a way that is both accurate and accessible. Bill's experience testifying in digital marketing cases helps ensure that his presentations are well-prepared and clearly delivered.
Consulting with Counsel
In addition to formal expert witness roles, Bill provides consulting support to legal teams. This may include reviewing discovery materials for digital marketing significance, helping counsel understand technical concepts and platform-specific terminology, evaluating opposing expert qualifications, assisting with deposition preparation for digital marketing witnesses, and identifying additional data sources that could strengthen or weaken a case.
Digital Marketing Channels Covered
Paid Search Advertising (PPC)
Analysis of Google Ads, Microsoft Advertising, and other paid search platforms, including campaign structure, keyword targeting, bid strategies, ad copy, landing page performance, Quality Score, conversion tracking, and return on ad spend. Disputes involving PPC often center on agency performance, mismanagement, unauthorized spend, or failure to implement proper tracking.
Learn more about PPC expert witness services →
Search Engine Optimization (SEO)
Evaluation of organic search strategies, technical SEO configurations, content optimization, link building, site migrations, and their effects on search rankings and traffic. SEO disputes may involve agency negligence, failed migrations, competitive harm, or claims about the value of organic search traffic as a business asset.
Learn more about SEO expert witness services →
Social Media Marketing
Review of social media advertising campaigns on Meta (Facebook and Instagram), LinkedIn, YouTube, TikTok, and X (formerly Twitter), including targeting strategies, ad performance, audience development, and organic social content. Disputes may involve claims about campaign mismanagement, inflated performance metrics, or failure to meet contractual obligations.
Learn more about social media marketing expert witness services →
Display and Programmatic Advertising
Analysis of display ad campaigns, demand-side platforms (DSPs), ad exchanges, viewability metrics, brand safety, ad fraud, and invalid traffic. These cases often involve questions about whether ads were actually seen by real users, whether they appeared alongside inappropriate content, and whether the reported performance metrics are accurate.
Learn more about display and programmatic advertising expert witness services →
Email Marketing
Evaluation of email marketing programs, including list management, deliverability, CAN-SPAM compliance, campaign performance, and subscriber engagement. Disputes may involve unauthorized use of email lists, misleading email content, or damage claims resulting from deliverability issues.
Learn more about email marketing expert witness services →
Analytics, Attribution, and Measurement
Validation of analytics implementations, conversion tracking configurations, attribution models, and marketing ROI calculations. This area is increasingly important in litigation because many damages calculations and performance claims depend on the accuracy and reliability of the underlying measurement systems.
Learn more about analytics and attribution expert witness services →
Platform Experience
Bill has direct, hands-on experience with Google Ads, Microsoft Advertising, Google Analytics (UA and GA4), Google Search Console, Meta Ads Manager, LinkedIn Campaign Manager, YouTube Ads, programmatic DSPs, major email marketing platforms, call tracking systems, CRM platforms, and leading third-party SEO and analytics tools.
Types of Cases
Bill's digital marketing expert witness work spans a range of case types, including the following. View all case types →
- Agency and consultant disputes — breach of contract, negligence, and performance claims involving digital marketing providers
- False advertising and deceptive practices — analysis of advertising claims, landing pages, and promotional content for accuracy and compliance
- Click fraud and invalid traffic — investigation and quantification of fraudulent activity in paid advertising campaigns
- Trademark infringement in digital advertising — analysis of keyword bidding, ad copy, and competitor targeting practices
- Traffic loss and revenue damages — reconstruction of marketing performance to quantify losses caused by the actions of another party
- Attribution and analytics disputes — evaluation of measurement accuracy and reliability in cases involving performance-based compensation
- Website migration failures — analysis of technical and marketing impacts of platform changes, redesigns, and domain transitions
- Defamation and online reputation — assessment of how negative content affects digital marketing performance and customer acquisition
- E-commerce and marketplace disputes — analysis of product listing optimization, marketplace advertising, and competitive practices on platforms like Amazon
- Data privacy and compliance — evaluation of marketing data collection, cookie consent, and compliance with applicable regulations
Methodology
Every engagement follows a structured methodology designed to produce opinions that are evidence-based, transparent, and defensible. The process typically includes the following steps. Learn more about methodology →
- Comprehensive review of available data from marketing platforms, analytics systems, contracts, and communications
- Identification of relevant time periods, key events, and baseline performance metrics
- Analysis of what actions were taken, what results occurred, and whether a causal connection exists
- Consideration of alternative explanations, including market changes, algorithm updates, competitive activity, and the client's own actions
- Quantification of impact using accepted analytical methods appropriate to the case
- Presentation of findings in clear, organized reports with supporting documentation
Daubert compliance: Bill's methodology is designed to meet the requirements of Daubert and other applicable evidentiary standards. His analyses are based on sufficient facts and data, employ reliable principles and methods, and apply those methods reliably to the facts of the case.
Next Steps
If your case involves digital marketing issues that require expert analysis, Bill Hartzer is available to discuss the specifics of the matter and help determine whether expert involvement is warranted.