About Hartzer Consulting

What this site is

trialwitness.com is a general reference on expert witnesses and expert testimony. It covers the role itself, the admissibility framework that governs opinion evidence in federal and state courts, and the sequence of an engagement from the first approach through disclosure, deposition and trial.

It has no subject matter of its own. The pages here describe what a rule requires, how a motion under it is briefed and decided, what a report has to contain, and what happens when a disclosure is late — questions that arise identically whether the opinion at issue concerns metallurgy, accounting, medicine or anything else. Where an example is needed, it is drawn generically, because the framework does not change with the field.

The site is written for an attorney who has just concluded that a case needs an expert, or that the other side’s expert is vulnerable. It is also read by students and researchers, particularly on the admissibility material, and that readership is served the same way: by being accurate, complete and specific about what is settled, what is split and what is simply unresolved. Every page is written to be useful to a reader who will never make contact.

Who publishes it

The publisher is Hartzer Consulting, a consultancy that accepts expert witness engagements from counsel. That relationship is stated plainly rather than hidden behind an editorial voice, because a reader is entitled to know who wrote the reference material and what they do for a living.

It also explains the site’s structure. A practice that testifies has a direct interest in the accuracy of what it publishes about testifying, since every page here is a document that could be put in front of the person who wrote it, under oath, by an examiner who has read it more carefully than most readers ever will. That is a stronger discipline than an editorial policy.

Hartzer Consulting is retained by counsel on both sides of the caption, in consulting and in testifying roles. Nothing on this site is written to favor plaintiffs or defendants, proponents or opponents of expert testimony, and the material on challenging an opinion is written with the same care as the material on getting one admitted.

The expert behind it

Bill Hartzer is the expert behind Hartzer Consulting and the practitioner whose experience informs this site. He has been working in digital marketing since 1996, and his expert witness work sits in technical disciplines connected to that background — the analysis of digital records, online platforms and the systems that generate them.

His engagement history includes retention by counsel in litigation matters, preparation of written reports under the federal disclosure rules, deposition testimony and testimony at trial. The specific record is published on this page from a single data file rather than restated in prose, so that it stays consistent across every site in which it appears and does not drift as the record changes.

What that experience contributes to a reference site is a particular kind of accuracy: the difference between what a rule says and what actually happens under it. A rule text will say that drafts of an expert report are protected. It will not tell a reader that the expert’s own notes of a conversation with counsel are generally treated as outside that protection, that the question is asked in almost every deposition, or that the answer is easier to give when the file was preserved rather than curated. The material on this site is written from both sides of that line.

Why the site is written in the third person

Reference material and marketing material do not read the same way, and the distinction is not cosmetic. A page that says the proponent must establish each requirement of Rule 702 by a preponderance is stating the law. A page that says the same thing in the first person is offering an opinion about it, and invites the reader to weigh the author before weighing the rule.

So this site is written institutionally throughout. It states what a rule requires, what a court held, what is contested and what remains unresolved, and it attributes practitioner experience by name and sparingly, only where a rule citation cannot carry the point. Hartzer Consulting’s other publications are written in the first person, because they are about a person’s own work. This one is about a field.

How the material is sourced

Every factual claim on this site traces to a primary or clearly identified source: rule text, an Advisory Committee note, a reported opinion, a statute, an ethics opinion, or a named study whose publisher, date, sample and method are stated on the page that uses it.

Three conventions follow from that, and they are visible on nearly every page.

Cases are described by what they actually decided. Court, year and citation, with the holding distinguished from dictum and from the version in circulation. Several of the most frequently cited decisions in this field are routinely mis-described in secondary writing, and where that is so, the page says which version is wrong and why.
Effective dates are given. Federal Rule of Evidence 702 was amended effective 1 December 2023; Federal Rule of Evidence 107 took effect on 1 December 2024, amending Rule 1006 with it; the expert provisions of Rule 26 of the Federal Rules of Civil Procedure are as amended effective 1 December 2010. A page that describes a rule without its date is describing an unknown version of it.
Disagreement is reported as disagreement. Where district courts are split four ways, where circuits apply materially different sanctions tests, or where a survey figure comes from a company that sells to the people it surveyed, the page says so. A reference that reads as though everything were settled is a reference that will mislead a reader at the exact moment they most need it not to.

What this site does not do

Several things are deliberately absent, and the omissions are as considered as the content.

It does not give legal advice. Nothing here is an assessment of any reader’s matter, and reading it creates no professional relationship of any kind.
It does not name clients or matters. No case studies, no engagement narratives, no figures attached to any particular retention.
It does not publish a rate. The material on fees explains what published surveys measured, how an expert quote is structured and what drives the size of a bill, without stating what this practice charges. A rate belongs in a conversation about a specific engagement.
It does not rank or compare expert witness directories, brokers or referral services. Those markets are described structurally — who pays, what a listing establishes and what it does not — without naming or ranking the businesses in them.
It does not predict outcomes. Rules require, courts have held, motions sometimes succeed. Nothing on this site says what any particular court will do.

Currency and corrections

Evidence and procedure move, and material about them goes stale in identifiable ways: a rule is amended, a state changes its admissibility standard, a split resolves, a survey publishes a new edition. Pages here carry the dates that let a reader see which version is being described, and are revised as those dates change.

Corrections are welcome and taken seriously, particularly on citations, holdings and effective dates. A message identifying a page, a passage and the authority that contradicts it is more useful than any other form of feedback this site receives, and it will be checked against the primary source rather than against another secondary summary.

Making contact

Enquiries from counsel are handled through the contact page, and the first step in every one of them is a conflict check. Until that check clears, a first message should describe the parties and the question in general terms and should carry nothing privileged, nothing confidential and nothing produced under a protective order.

Enquiries that are not about an engagement — from students, researchers, journalists and other practitioners — are welcome on the same terms. Questions about how the framework works can be answered generally. Questions about whether a particular expert should be excluded, or whether a particular opinion will be admitted, cannot be, and are not answered here.

The engagement record

Working in the field since: 1996
Expert reports: 36
Depositions: 8
Trials: 5
Arbitrations: 1