Why tribunals distrust the black box

An expert’s report is not judged on whether its conclusions are plausible. It is judged on whether the tribunal can follow the route from the record to the conclusion and, at each step, see the document that supports it. A report that asks to be trusted rather than checked is at a structural disadvantage before the first question in cross-examination.

Where opinions break

The weak points are rarely the headline conclusions. They are the intermediate assertions: that a design change was issued on a particular date, that a subcontractor was instructed before or after a hold, that a programme revision reflected a decision already taken. Each of these is a factual claim with a documentary basis somewhere in the record. When that basis is not cited, opposing counsel does not need to prove the assertion false. They need only show that it cannot be verified.

What admissibility now demands

The direction of travel in arbitral practice is towards transparency of method: the data relied upon, the steps taken, and the sensitivity of the result to alternative assumptions. An analysis whose every assertion opens to its source is not a stylistic preference. It is the form in which delay evidence is increasingly expected to arrive.