The Commercial Court gave short shrift to parties calling insurance experts to opine on meaning of a widely used construction insurance policy. The case of Aspen Insurance UK Limited v Adana Construction Limited  EWHC 1568 (Comm) concerned cross claims for declarations as to whether the claimant insurer was contractually bound to cover the defendant contractor under the terms of a combined liability insurance policy. The defendant was joined in proceedings for damages for personal injury sustained by a crane driver following the collapse of some foundation piles. One issue of note in this case was the way the trial judge treated the issue of insurance experts. The Claimant was given permission at the CMC to call expert evidence from an Insurance expert with wide experience of the combined contractors' liability insurance policy placed in the Lloyd's Market and of the market in which such insurance is placed. The expert was to address the contention that there was a conventional understanding as to the division between public liability and product liability, with the latter cover 'kicking in' exclusively once the Defendant's works had been handed over. According to the Claimant such conventional understanding formed part of the factual matrix of the policy and it was said that that understanding was of assistance in construing the terms of the contract. The judge at the CMC gave permission but left the issue of the admissibility of the expert evidence to the trial judge. At the start of the trial the judge expressed reservations about the relevance and admissibility of the expert evidence but agreed to hear it. The Claimant duly called their expert. The Defendant called evidence in rebuttal. In his judgement Mackie J did not mince his words when expressing his views on the use of such experts: "I expressed reservations about the relevance and admissibility of this evidence at the outset but agreed to hear it. In one sense the Claimant got what it deserved, first responsive evidence from the Defendant even more inadmissible than its own and secondly emergence of a recent example of the Claimant having acted inconsistently with its alleged market understanding .... [the experts'] evidence was irrelevant". The experts had given evidence that included admitting that it was from their interpretation of the contract that they drew their views. On issues of contractual interpretation parties would be well advised before attempting to call expert evidence as to industry use or practice relating to those terms, to conduct a proper analysis of the reason that evidence is necessary. If the evidence simply corroborates one party's understanding of the interpretation then the evidence is likely to be inadmissible or irrelevant. However if a party could demonstrate that industry knowledge and practice informed the contractual intentions of both parties in relation to the disputed provisions then it may be appropriate to request permission for such experts.