The most consequential decisions an expert witness makes on a case are often the first ones — before a single page of the report is drafted. Whether to accept the instruction at all, on what terms, and with what caveats, sets the trajectory for everything that follows. Get this stage right and a great deal of later difficulty is avoided. Get it wrong and no amount of drafting skill can fully repair the damage.
The threshold question: should the instruction be accepted at all?
Before confirming an appointment, a construction or engineering expert should be satisfied on three points:
- Competence. Does the expert genuinely have the experience, knowledge, and expertise the assignment requires — not adjacent experience, but the specific competence the dispute demands? A quantity surveyor experienced in building disputes is not automatically qualified to opine on marine works or rail systems engineering.
- Capacity. Can the expert actually deliver the work to the required standard within the timetable the tribunal has set? Overcommitted experts producing rushed reports are a recurring cause of credibility problems at hearing.
- Independence. Is there anything — a prior relationship with a party, a previous engagement on a related matter, a financial interest — that could compromise, or be seen to compromise, the expert's ability to give impartial evidence?
Where any of these give the expert genuine pause, the professional response is not to quietly proceed and hope the problem doesn't surface. It is to raise it candidly with the prospective client before instructions are confirmed — including circumstances that might cause a tribunal to attach less weight to the eventual evidence.
What should be confirmed in writing before work begins
A properly documented instruction protects both the expert and the instructing party, and it produces a paper trail that stands up well if instructions are later challenged. Before starting substantive work, the engagement should establish in writing:
- The precise scope of the questions on which expert evidence is required
- The applicable procedural framework — whether DIAC Rules, DIFC Courts practice, arbitrateAD procedure, or another institutional or ad hoc regime — and the standards that will govern the expert's conduct
- The basis of the expert's fees, confirmed as an hourly rate or fixed fee rather than any form of conditional or outcome-linked arrangement (a point explored further later in this series)
- Whether any part of the assignment will be carried out by someone other than the named expert, and if so, by whom and under what supervision
- Confirmation that the expert's report and evidence will be independent, and that this duty overrides any obligation to the instructing party
This last point is worth stating plainly to the client at the outset, not left implicit. Clients unfamiliar with arbitration — particularly private clients or contractors engaging an expert for the first time — sometimes arrive with the expectation that the expert is simply another member of the case team. Setting that expectation correctly from the first conversation avoids friction later, when the expert's independence produces conclusions the client did not anticipate.
Off-the-record instructions are a recurring trap
One of the more damaging patterns in expert evidence is the informal, undocumented instruction — a phone call, a margin note, a verbal steer given in a corridor conversation — that never makes it into the written record but nonetheless shapes the expert's approach. Tribunals are alert to this, and cross-examination on the completeness of an expert's instructions is a standard and legitimate line of attack. An expert whose written record of instructions is incomplete, or who has to concede that "off the record" guidance shaped the analysis, hands the opposing party an easy route to undermining the report's credibility.
The discipline here is straightforward, if sometimes inconvenient: every instruction of substance, however it arrives, should be captured in writing and retained as part of the expert's file.
A note for contractors and engineering businesses
For a contractor bringing or defending a claim, the temptation at this stage is often to move quickly — find an expert, get a report drafted, keep the claim moving. That instinct is understandable but can be costly. An expert engaged without a clear scope, without confirmed independence, or without a documented instruction trail is a liability waiting to surface at the worst possible moment: under cross-examination, mid-hearing, with no opportunity to correct the record. The time invested in a properly documented instruction at the outset is, in a very direct sense, insurance against that risk.
Part 4 turns to conflicts of interest specifically — how to identify them, what to do when one emerges after instructions have already been accepted, and why disclosure is almost always the safer course.