Can I get a (expert) witness?

The objective of an expert witness


Deciding if an expert is needed – and if so, what kind – must be addressed before beginning a search for an expert witness.


When the facts and issues of the case are not easily comprehensible – when they fall outside the common experience of judges and juries – an expert is needed to provide and share relevant knowledge to the courtroom. Highlighted by Section 4 of the Evidence Act, an “expert” is defined as “a person who specialised knowledge or skill based on training, study, or experience.”


Once introduced, the purpose of expert evidence is to enlighten the court in fields outside common knowledge. According to the New Zealand Law Society, there are two types of expert evidence:


1) Factual evidence of the expert’s own investigations and observations. For example, a pathologist might describe the state of a corpse during autopsy, a ballistics expert might describe the characteristics of a cartridge case, or an engineer might describe the physical state of a car’s brakes


2) Opinion-based evidence includes inferences or conclusions drawn from studying the facts. Opinion is defined in the Evidence Act as “a statement of opinion that tends to prove or disprove a fact”. For example, the pathologist might suggest the cause of death; the ballistics expert might suggest that the bullet found in the body could have been fired from a certain gun; the engineer might comment that the brakes were incapable of safely stopping the car from a stated speed within a certain distance.


Even if there is not a great deal of complex jargon to be explained, an expert witness can still be crucial in offering insight into the case that people might not consider.


But what makes an ideal expert witness?


Three important characteristics in choosing an expert witness


Independence of view, which is a requirement of the Code of Conduct. The expert witness needs to be objective.

Qualifications in the required area of expertise. Although not strictly necessary, formal qualifications are an advantage.

Relevant and recent experience in the area. For example, positions held, actual projects, and responsibilities.


Not every professional or advisor makes a good expert witness.


Rather than pushing in favour of the client’s position, the expert witness is required to provide objective insight. That means that while technically they could support either side of the case. Ultimately, the expert witness is there to assist the court and not advocate for one party or the other.


The ideal expert witness will be known to have strong ethics and independence. The witness should have no previous relationship with anyone involved in the case, and will not be motivated to aid either side.


In regards to their relevancy and qualifications criteria, there are several key questions you should ask when considering whether someone as an expert witness.


Has the expert witness regularly performed the task at issue? It puts your case in a great disservice to have an expert witness who does not have relevant qualifications in their field. An expert witness who isn’t currently practicing is also problematic as is one who just completed their education last week.


Has the expert witness been published on the subject? A published expert witness can explain to the jury that their opinions have withstood industry scrutiny, which helps show their authority to offer opinions in your case.


Can the expert witness speak confidently and clearly? An expert witness must know what they are talking about and be able to explain their statements clearly in a public forum. Evidence of presentations or teaching may showcase the ability of the expert witness articulate their opinion to others.


The ideal expert witness is experienced, active and recognised. It is someone with the appropriate amount of experience who will not be rattled when the opposing side in the case tries to discredit their testimony, which they will attempt to do. Even if an expert witness has decades of experience in their respective field, a lack of experience in the courtroom can lead to them being unprepared in facing an onslaught of questions, challenging their confidence and – by effect – their expertise.


The final verdict


Many strategies are adopted and utilised during high-stakes litigation, but securing the right expert witness testimony is perhaps the most critical and decisive part of the strategy. Expert evidence can be the factor in winning or losing a case.


Any insights on what makes a perfect expert witness? Need help choosing an expert witness? Please email Matt at or John at