What Lawyers Wish Their Expert Witnesses Knew (An Insider’s View)

1. Your Duty is Not to the Client – It’s to the Court

This is the “Golden Rule” of expert evidence, yet it is the one most frequently misunderstood by newcomers. In the adversarial system, it is natural to feel a sense of loyalty to the party paying your invoices. However, from a legal perspective, your primary allegiance is to the Court.

Under the Harmonised Expert Witness Code of Conduct, which is applied across federal and most state jurisdictions in Australia, an expert has a paramount duty to assist the court impartially.  This same obligation also exists in the other Australian jurisdictions.

What lawyers wish you knew:

When an expert acts like an “advocate” for the client, they lose their value. A lawyer cannot use a biased report because it will be shredded under cross-examination. Instructing solicitors actually want you to be “fearlessly independent.” If the facts are against their client, they need to know that early in the piece so they can advise on a settlement, rather than being ambushed at trial.

2. The “Makita” Standard: Show Your Working

In Australian law, the landmark case of Makita (Australia) Pty Ltd v Sprowles established the criteria for admissible expert evidence. Many experts provide a brilliant conclusion but fail to explain the “prime deficiency” – the reasoning that led them there.

The Makita Checklist for Experts:

• Specialised Knowledge: Is the opinion based on your specific training or experience?
• Identified Basis: Are the facts you relied upon clearly stated?
• Proven Facts: Can those facts be proven by other evidence?
• Logical Link: Does your conclusion flow logically from those facts?

 

Common expert witness mistakes often involve what lawyers call “the ipse dixit” problem – asking the court to accept a conclusion simply because the expert said it. A lawyer wishes you would “show your working” as if you were grading a mathematics exam. If a judge cannot follow your logic and understand why you conclude what you do, your opinion is legally useless.

3. The Letter of Instruction (LOI) is Your Bible

The instructing solicitor will provide you with a Letter of Instruction. This document sets the boundaries of your “sandbox.”

Why the LOI matters:

• Scope: It defines exactly what questions you are – and are not – asked to answer.
• Assumptions: It lists the facts you must assume to be true for the purpose of your report.
• Admissibility: If you answer questions outside the LOI, you risk your entire report being ruled inadmissible.

Lawyers wish experts would read the LOI with surgical precision. If you find that the assumptions provided are factually incorrect based on your investigation, do not simply ignore them. Call the solicitor and explain why the instructions may need to be amended.

4. Jargon is the Enemy of Persuasion

You are hired because you know things the judge doesn’t. However, if the judge cannot understand your explanation, they cannot accept your evidence.

What makes a good expert witness is the ability to translate “high-level technicality” into “layperson’s logic.” Lawyers often spend hours “translating” expert reports for their own understanding; they wish the expert had done that work for them in the first place.

The “Grandmother Test“

Could you explain your conclusion to a reasonably intelligent person who has no background in your field? Use analogies. Use clear headings. Most importantly, keep your sentences short. If a sentence in your report is longer than three lines, it is probably too complex.

5. The Danger of “Scope Creep”

A common mistake is the expert who tries to be “too helpful.” You might be a structural engineer asked to comment on a balcony collapse. While on-site, you notice some electrical issues and decide to include them in your report to “add value.”

Don’t do it. By commenting on matters outside your specific field of expertise, you provide the opposing counsel with a “hook” to challenge your overall credibility. If you can be proven wrong or “unqualified” on the electrical issue, the court may begin to doubt your structural engineering conclusions as well. Consider and know the exact scope of your area of expertise and then stick to your lane.

6. Transparency Regarding “Unfavourable” Data

Every case has “bad facts.” Many experts think their job is to hide these facts or gloss over them. In reality, a lawyer’s greatest fear is an expert who ignores a contradictory piece of data, only for the opposing barrister to bring it up during cross-examination.

What lawyers need: An expert who acknowledges the unfavourable data and explains why it does or doesn’t change their final opinion. For example:

“I have considered the 2022 rainfall data which suggests lower moisture levels; however, this does not alter my conclusion regarding soil subsidence because…”

This proactive approach builds immense credibility and “bulletproofs” the lawyer’s case.

7. Formatting Matters More Than You Think

It sounds trivial, but a poorly formatted report is a nightmare for a legal team. In a trial, everyone – the judge, the barristers, the witnesses – needs to be on the same page, literally.

Professional Standards for Reports:

• Numbered Paragraphs: Essential for quick reference in court (e.g., “Witness, please look at paragraph 42 of your report”).
• Consistent Page Numbering: Ensure the report and the appendices are paginated.
• Executive Summary: A one-page “bottom line” at the beginning is invaluable for a busy judge.
• Appendices: Keep heavy data, CVs, and site photos in the back to keep the narrative flow of the report clean.

8. Mastering “Concurrent Evidence” (The Hot-Tub)

Australia is a world leader in “Concurrent Evidence,” colloquially known as “the hot-tub.” This is where experts from both sides are sworn in together and sit in the witness box at the same time to discuss their differences.

What the lawyer wishes you knew about the hot-tub:

It is not a debate; it is a peer-review session monitored by a judge. Lawyers often feel a loss of control during concurrent evidence because they cannot “lead” the witness as much. They need an expert who is:

• Collegial: You can disagree without being disagreeable.
• Flexible: Be prepared to concede a point if the other expert presents a valid scientific argument.
• Articulate: You must be able to hold your own in a room full of specialists without a lawyer to protect you.

Preparation for a “conclave” (the private meeting of experts before the trial) is a core part of our expert witness prep. A successful conclave can narrow the issues so significantly that it often leads to a settlement before the trial even begins.

9. Deadlines are Not “Suggestions”

The legal system operates on a rigid calendar of “Court Orders.” If a judge orders that expert reports must be served by 4:00 PM on a Friday, a delay of even one hour can have consequences, including the exclusion of the evidence or significant cost penalties for the client.

The Insider’s View: Solicitors often list “reliability and timeliness” as more important than “academic eminence” when choosing an expert. A Nobel Prize winner who delivers a report three weeks late is less valuable than a competent professional who delivers on time.

10. The Ethics of “Draft” Reports

There is a complex area of law regarding “Legal Professional Privilege” and draft reports. In some jurisdictions, every draft you write – and every email you send to the solicitor – could be discoverable by the other side.

Advice for Experts:

• Don’t write it down if you don’t want it read in court.
• Avoid “opinion-shopping” emails. Don’t send an email saying, “I can make the report say X if that helps your case.” This destroys your independence.
• Telephone first: Many solicitors prefer a phone call to discuss your preliminary findings before you put pen to paper. This ensures everyone is on the same page regarding the scope of the work.

Why Expert Witness Prep is the Missing Link

Most professionals are experts in their subject, but few are experts in the process of law. This is where many common expert witness mistakes occur. You might be the best surgeon in the country, but if you don’t know how to handle a hostile barrister or how to format a section 79-compliant report, your expertise is wasted.

Benefits of Professional Training:

1. Reduced Anxiety: Knowing the “rules of engagement” takes the fear out of the courtroom.
2. Increased Admissibility: Learn to write reports that survive legal challenges.
3. Higher Engagement Rates: Lawyers keep a shortlist of experts who are easy to work with. Training puts you at the top of that list.
4. Reputation Protection: Avoid the professional embarrassment of being criticised in a published judgment for lack of impartiality.