Part 2 of a 10-part series for clients navigating a dispute before the DIFC Courts or in DIAC arbitration.
One of the most common — and most costly — mistakes clients make early in a dispute is confusing three roles that sound similar but are legally very different: the expert witness, the witness of fact, and the advocate. Mixing them up can genuinely damage your case, so it's worth getting clear on the distinction before you go any further.
Expert witness
This is a person who, because of their qualifications, training, and experience in a technical field, is permitted to give the Court or tribunal their opinion — not just facts — on matters within that field. In a construction, engineering, valuation, or quantum dispute, this is typically a chartered surveyor, engineer, architect, or accountant.
Witness of fact
This is a person — which might be you, an employee, a contractor, or a site representative — who gives evidence of what they personally saw, did, or were told. A witness of fact is not permitted to offer opinions outside a narrow set of exceptions, and does not carry the same independence-based duties as an expert.
Advocate or legal representative
This is the person who presents your case to the Court or tribunal, examines and cross-examines witnesses, and makes legal submissions on your behalf.
Why this matters
Under both DIFC Courts practice and DIAC arbitration, the advocate role is ordinarily kept strictly separate from the expert witness role. If you're unrepresented, it can be tempting to lean on your expert for more than their technical opinion — asking them to also argue your case, draft your submissions, or speak for you at a hearing.
Resist that temptation. Blurring the two roles undermines the perceived independence of the expert's evidence, which is exactly what gives that evidence its value to the Court or tribunal in the first place. We'll come back to this in more detail in Part 10, including the narrow circumstances in which a dual role is even discussed.
For now, the takeaway is simple: know which hat each person in your dispute is wearing, and don't ask them to wear two at once.
Next: Part 3 — The Expert's Overriding Duty (and Why It Isn't to You).