Quantity Surveyor’s role as an expert witness for courts


The role of an expert witness is to assist the court or tribunal by providing objective, unbiased opinions on matters within their expertise during a dispute. For construction disputes, experts generally fall under three distinct headings:

  • Quantum Expert
  • Delay Expert
  • Technical Expert

Generally, a Certified Quantity Surveyor (CQS) is called upon by the court to provide expert opinion on the quantum and delay involved in disputes.

Who can carry out the Expert Witness role?

The quantity surveyor’s role as an expert witness should only be undertaken by an AIQS member holding the Certified Quantity Surveyor (CQS) designation with specific training in the field of expert witness services. There is, however, no substitute for experience.

The Quantity Surveyor’s role is to assist the court or tribunal

Expert evidence helps courts or tribunals make decisions. Although the decision-makers are highly qualified and experienced in law, they may not be specialists in every field that might come up at a trial.

If a case involves technical questions or analysis of a large amount of data, an expert may be asked to give evidence about a specific topic in order to help the court resolve the wider dispute.

An expert witness does not take over the role of the decision-maker. The court or tribunal will reach its own conclusion based on expert and other evidence presented in the case.

Duties and responsibilities of an expert

The appointed expert should be independent and uninfluenced. In other words, the expert must not be a “hired gun” advocating a case on behalf of their client. To demonstrate this independence, the expert’s evidence should be:

  • objective
  • unbiased
  • within their area or expertise

The guiding principle to expert evidence is that the expert’s first duty is to the court or tribunal.

What is an expert witness report?

An expert witness report is a document that describes the results of a quantity surveying investigation. The report will usually contain details about the scope of the investigation, including any limitations, a description of how the investigation was performed, a description of what was found during the investigation, and conclusions about those findings.

The purpose of an expert witness report is to provide information regarding the facts and circumstances surrounding a case. This may include providing opinions on these facts, but only if the opinion is based on factual findings from an investigation. For example, a quantity surveyor may provide an opinion regarding the cost of building a house based on their findings during an investigation.

At 41 MPa, we are well-qualified Certified Quantity Surveyors (CQS) with extensive experience providing expert court witness services nationwide.

QS glossary

Scroll to Top