Expertise with expert ease: Learning to be an expert witness

By Nikki Pender

The importance of an expert witness

Expert witnesses play a special role in legal proceedings. Their evidence assists judges, juries, tribunals and arbitrators to resolve complex, issues. A well-written report can also soften the intractability of party positions enough to facilitate settlement negotiations.

The special nature of expert evidence

Evidence is produced in a case to prove facts, often contentious ones. The evidence of fact witnesses tends to be sensory; they recount something they saw or heard or did. These witnesses are typically not asked to draw inferences from the evidence they give, as that is the decision maker’s responsibility. The rules of evidence also limit the ability of witnesses to proffer an opinion.

Expert evidence is different. The specialist knowledge of expert witnesses entitles them to draw inferences from factual evidence that is complex and beyond the general understanding of non-experts. For example, the evidence of body samples taken from a crime scene may be used to infer that a particular person had been there. But the samples must first be scientifically tested. And the test results themselves are unlikely to mean much to a jury without explanatory evidence from a forensic scientist.

The courts permit expert witnesses to give opinion evidence because it assists the decision maker and, without it, the case could not be fairly determined.

With privilege comes responsibility

More is expected from experts than from other witnesses. The paramount duty of an expert witness is to assist the court impartially on matters that fall within their area of expertise. This remains the case whether he or she is paid by the court itself or by one of the parties. The courts take this requirement seriously and may be critical of an expert witness who fails to meet the requisite standard of independence. 

Yet, retaining objectivity can be easier said than done. How does an expert witness remain independent when they are engaged (and remunerated) by one of the parties? And where exactly does acceptable persuasion end and unacceptable advocacy begin?  

The power of a well-written report

As an expert, the first thing that you will be asked to do is prepare a report. Your expert report may be the only evidence you produce; or, if you are required to attend court, it will be the focus of any cross examination. 

Never underestimate the power of a well-written report.

Some experts provide evidence multiple times without ever being cross examined, simply because their written evidence was enough to resolve the issue.  For example, valuation or financial evidence that persuades the parties to agree quantum ahead of trial.

The courts have strict rules about what should be included in expert reports. You must understand these rules and comply with them for your evidence to be accepted. Effective and accessible writing is also vital.

Withstanding cross examination

Most New Zealand court proceedings are adversarial; cross-examination of witnesses by the lawyer for the opposing side is one of the fundamental dynamics on which this system is based. As an expert witness, it is something that you will need to be prepared for.

The secret to dealing with a tough cross-examination - and they will be tough - is always the same: be professional, calm and remember that you are there to be of service to the court, tribunal or arbitration.

Expert witnesses also need confidence, mental dexterity, and a plain-English style of communication. The foundation of your evidence needs to be robust enough to withstand the whittling-away attempts of cross examiners; but you must also be prepared to adapt your opinion if the underpinning materially changes. And don’t assume that a Judge will accept your opinion just on your say-so. Your evidence may be that of a suitably qualified technocrat in a suitably technical area, but it still needs to make sense to a lay person.

The ability to explain a complex subject simply is a measure of mastery; it is also a core competency for expert witnesses.

The heat of a hot tub

Increasingly, expert evidence is examined in court using the curiously named “hot tub” method (aka “concurrent expert evidence”). While protocols can vary from court-to-court, this process generally involves an expert witness for one party and his or her counterpart for the other side sitting and being examined together.

Before getting to court, the experts usually also meet to crystallise the points in dispute and prepare a joint report. ‘

The biggest challenge here is being able to hold your own in a conclave of your peers.

Honing your skills

The expert witness arena is fascinating, well-paid and can add a new dimension to a career. It is also a way of contributing something important to society. But it’s no place for amateurs. You do need a basis understanding of your role and of the rules that govern expert evidence. There are also some key skills and competencies that can be developed if you are thinking of venturing into this line of work.

Nikki Pender is a barrister at Kate Sheppard Chambers and the founding director of Legal Empowerment Ltd. Nikki has been training expert witnesses since 2016.