Some experts treat caveats as a sign of weakness — a hedge that undermines the authority of the opinion. In reality, the opposite is true. Precise, well-placed caveats are one of the clearest signals of a rigorous, trustworthy expert, while their absence is one of the fastest ways to invite a credibility problem later in the proceedings. This piece looks at how to handle assumptions, instructed facts, and provisional opinions correctly.
Why caveats build credibility rather than undermine it
A report that reads as unqualified and definitive on every point, in a dispute where the underlying evidence is genuinely incomplete or contested, tends to strike an experienced tribunal as either naive or partisan — neither of which serves the instructing party well. By contrast, a report that says plainly "this opinion is provisional, because X information has not yet been made available, and my conclusion may change if Y emerges" demonstrates exactly the kind of independent, evidence-led thinking that gives an expert's other, more confident conclusions greater weight. Tribunals trust experts who show their working and are honest about its limits.
Distinguishing what the expert has been told to assume
Where an expert has been instructed to proceed on a particular factual basis — for example, to assume a specific completion date, or to take a disputed variation instruction as validly issued — that instruction must be identified explicitly in the report as an assumption, not folded silently into the analysis as though it were established fact. This matters for two reasons.
First, it allows the tribunal to understand precisely what the opinion depends on, and to test that dependency: if the assumed fact is not ultimately established, the tribunal can see immediately which conclusions in the report are affected and which are not. Second, it protects the expert. An expert who has clearly flagged an instructed assumption cannot later be accused of having independently verified something they were, in fact, told to take as given.
When a final, unqualified opinion cannot be given
There will be cases — more often than newer experts expect — where the available information simply does not support a definitive conclusion. This might arise because:
- Key documents have not been disclosed or made available
- The physical evidence (for example, in a defects claim where remedial works have already taken place) can no longer be directly examined
- The methodology available produces a range of plausible outcomes rather than a single defensible figure
- Further expert conferencing or clarification of instructions is needed before the analysis can be completed
In any of these situations, the professional obligation is to say so directly: to indicate where, in what way, and why an opinion is provisional, what further information would allow it to be finalised, and — if a final and unqualified opinion genuinely cannot be given — to say that plainly rather than presenting a qualified view as though it were conclusive.
What this means for quantum reports specifically
Quantum experts working from incomplete cost records — a frequent reality on long-running mega-project disputes where documentation has passed through multiple subcontractor tiers — face this issue often. The temptation to fill gaps with reasonable-seeming estimates, without flagging that an estimate has been made, is one of the more common ways quantum evidence loses credibility under cross-examination. Better practice is to present a range where the record genuinely supports one, explain the basis for any estimate used to bridge a documentary gap, and be explicit about which components of the final figure rest on verified data and which do not.
A note for private clients and contractors reading an expert's report for the first time
If you are a party to a dispute reviewing your own expert's report, a report full of careful qualifications and provisional statements is not a sign that your expert lacks confidence in your case. It is very often the opposite: a sign that the expert has approached the evidence with the rigour a tribunal will respect. An expert whose report contains no caveats at all, on a dispute of any real complexity, is worth asking hard questions about — because either the underlying evidence was unusually clean and complete, or the caveats that should have been there were simply left out.
The discipline in practice
Before a report is finalised, every conclusion should be tested against a simple question: is this genuinely established by the evidence, or does it depend on an assumption, an estimate, or an incomplete record? Where the answer is the latter, the report needs to say so — not as a defensive afterthought, but as an integral part of presenting the opinion honestly.
Part 10 addresses what happens when, after a report has already been disclosed, the expert's opinion changes — and how to handle that without undermining the credibility built up to that point.