When it goes wrong

Conflicts: decided on the retainer

A conflict of interest is usually decided on the expert's contract. In Secretariat Consulting Pte Ltd v A Company a group's Singapore company had been retained to give delay evidence for an employer in an arbitration about a petrochemical project. A sister company then took an engagement in a second arbitration about the same project, on the other side from that employer. The Court of Appeal upheld an injunction against the second engagement. The retainer contained an express term that there was no conflict and that none would arise. Read with the group-wide conflict check and the group's one-firm marketing, that term bound the whole group ([69] to [81], [116] to [122]). A group can limit such a term to the entity instructed if it chooses ([101], [123]).

The court did not hold that experts are fiduciaries. Coulson LJ decided the case on the retainer rather than on a freestanding fiduciary duty ([100]). Males LJ said that, save perhaps in cases far removed from that one, an expert witness is not a fiduciary ([104]), and that the relationship between expert and client is essentially contractual ([105]). The same expert can act for and against the same client on other matters. Conflict is a matter of degree ([98]).

Two further rules sit beside it. A conflict does not disqualify an expert by itself: the key question is whether the opinion is independent (Toth v Jarman [100]). But the expert must disclose any conflict that is not obviously immaterial, at the latest when the report is served ([108], [112]). Whether it is material is for the court to decide, not the parties ([112]). In Hong Kong, connections with a party go to weight even where they do not exclude the evidence. In Redland Precast the expert had acted as the party's representative in the mediation. The Court of Appeal said that such connections, and an apparent interest in the outcome, may affect the weight of the evidence ([31]). In an arbitration under the Arbitration Ordinance the tribunal is not bound by the rules of evidence and gives the evidence the weight it considers appropriate (s.47(3)).

“the relationship between the expert and his client is essentially contractual.”

“But a conflict of interest is a matter of degree.”

“Save perhaps in circumstances far removed from the present case, an expert witness is not a fiduciary and does not owe fiduciary duties to his client.”

“it is for the court and not the parties to decide whether a conflict of interest is material or not.”

“The connections that an expert has with a party and the apparent interest he has in the outcome, even if insufficient to preclude him from giving evidence, are relevant factors that may affect the weight to be placed on his evidence.”

Failures of duty: what the courts did

When an expert breaks the rules, the English courts have refused or withdrawn permission to call the evidence at all. Four cases show the main ways it happens. In ICI v MMT the quantum expert decided for himself how the contract should be read and argued for it ([184] to [187]). He also took positions on disputed facts in his client's favour ([197] to [199]). Fraser J found that all four of that party's experts lacked independence ([233] to [235]). He set out six rules at [237]. Two of them matter most here: experts of like discipline should have the same material, and it is not the expert's place to choose between versions of the facts. In Dana v Freudenberg the client's in-house specialists had dealt directly with the experts, nothing was recorded, and the experts visited sites without telling the other side ([72] to [84]). On day 7 of the trial the court refused permission for all three experts ([61] to [64], [87]). The judge added that lawyers must supervise experts from other jurisdictions ([93]).

The joint statement is where lawyers and clients most often go wrong. In Glover the claimants' solicitors made tracked changes to the expert's draft joint statement and stripped the metadata; the opposing expert noticed that the changes read like lawyers' work. Permission was revoked ([70]). In Marples the claimant himself, a trained accountant, rewrote his own expert's side of the joint statement with about 150 amendments. He then asked the expert to make sure his contribution was deleted from the track changes. The expert also had an undisclosed earlier business connection with him. Permission was refused ([30] to [46]). In Tata v DBS the quantum expert assessed a claim over six years when the pleaded claim covered three. The judge said this was the expert advancing a new case, which is not the role of an expert ([479]). Three more cases are in the same line. In Andrews v Kronospan the solicitors commented on drafts of the joint statement; permission was revoked although about £255,000 had been spent on fees. In Vainker v Marbank the expert accepted that he had been instructed not to sign the second joint statement, contrary to his duty ([58]). In Cabo v MGA the experts abandoned positions during the trial ([48] to [49]).

A Hong Kong tribunal has different tools. In court, a breach of the Code of Conduct goes to the weight of the evidence, not its admissibility, once the expert's declaration has been given (Harvest Treasure [22]). In arbitration the tribunal is not bound by the rules of evidence and gives the evidence the weight it considers appropriate (Cap 609 s.47(3)). Where the CIArb Protocol applies, a tribunal satisfied that an expert's evidence does not match the declaration must disregard it, in whole or in part, as it considers appropriate (art 7.4). The tribunal can also reflect wasted time in costs. Refusal of permission is a court sanction, and so is contempt for a false statement in a report (Liverpool Victoria v Zafar [59] to [61]). Neither is the arbitral tool.

“There are some jurisdictions where partisan expert evidence is the norm. For the avoidance of any doubt, this jurisdiction is not one of them.”

“the use of experts only works when everyone plays by the same rules.”

“could be grounds for challenging the weight of his evidence, they should not be a ground for holding that such evidence is inadmissible.”

“it is not the place of an independent expert to identify which version of the facts they prefer. That is a matter for the court.”

“Where a joint statement is prepared pursuant to CPR 35.12 it is prepared for the benefit of the Court, not as a means of advancing the case of one or other party”

“substantial and impermissible interference in the expert statement process by those acting for the claimants.”

“This is not the role of an expert.”

“the Arbitral Tribunal shall disregard the expert's written opinion and testimony either in whole or in part, as it considers appropriate in all the circumstances.”

AI: the rules are moving towards disclosure

Hong Kong has no rule on an expert's use of artificial intelligence. The Judiciary's July 2024 guidelines on generative AI are internal, written for judges and their staff, and say nothing about experts; they ask judges to be aware that court users may have used generative AI. HKIAC has issued no AI guidance. The Department of Justice's consultation on the Arbitration Ordinance, which ran from 28 September to 27 October 2026, recommends no amendment on AI for now. These positions were checked on 3 October 2026.

Elsewhere the direction is disclosure. The clearest rule is in Ireland. High Court Practice Direction HC 142 was issued on 29 July 2026 and came into operation on 1 September 2026. It requires every expert report to carry a declaration at the start that generative AI has not been used to generate its substantive content (para 29). If it has, the expert must disclose the nature and extent of the use so that the court and the parties can assess the reliability, independence and weight of the opinion (para 30). New South Wales goes further. Under Supreme Court Practice Note SC Gen 23 (in force from 3 February 2025), generative AI may not draft any part of an expert report without the court's prior leave (para 20). With leave, the report must say which parts, which program and which version (para 22). Lawyers must draw the rules to experts' attention when they instruct them (para 24). The Federal Court of Australia's practice note GPN-AI (16 April 2026) says an expert report should contain the expert's own opinion and reasoning (para 4.9). AI used to summarise or analyse the material the expert relies on must be disclosed (para 4.10).

Professional bodies are moving the same way. The RICS standard Surveyors acting as expert witnesses, 5th edition (July 2026), takes effect on 30 November 2026, three weeks after this webinar; the 4th edition applies until then. It applies to RICS members worldwide, so to many of the quantity surveyors who give evidence in Hong Kong arbitrations. From that date a member's evidence must be their own work, and any work done at their direction, including material generated through AI, must be identified as such (s 4.1.1(b)). The member must also confirm in writing at the outset if AI is likely to do part of the assignment (s 3.2.1(3)(b)).

In England and Wales there is a proposal, not a rule. The Civil Justice Council's interim report of February 2026 proposes an addition to the expert's statement of truth in Practice Direction 35 (para 8.2). The expert would explain what use of AI has been made, other than for transcription or other administrative uses, and identify the tools used. The final report was expected later in 2026. For arbitration, the CIArb Guideline on the Use of AI in Arbitration was first published in March 2025 and updated in September 2025. It is not binding. It says arbitrators may impose AI disclosure obligations on the parties, including party-appointed experts and fact witnesses (para 7.3). They may draw adverse inferences from non-disclosure, or reflect it in costs (para 7.7). A Hong Kong tribunal can adopt the same approach in its first procedural order.

“arbitrators may impose certain AI-related disclosure obligations on the parties including any party-appointed experts or factual witness”

“There is no immediate need to amend the AO in relation to the use of artificial intelligence in arbitration.”

“Generative Artificial Intelligence has not been used for the purposes of generating the substantive content of this report which reflects my own opinions, knowledge and evidence.”

“the expert must disclose the nature and extent of that use to the extent necessary to enable the Court and the parties properly to assess the reliability, independence and evidential weight of the opinion expressed”

“Gen AI must not be used to draft or prepare the content of an expert report (or any part of an expert report) without prior leave of the Court.”

“be entirely their own work except where some work is carried out at their direction and under supervision (including material generated through artificial intelligence), in which case the member's evidence must make it clear which items of work have been carried out this way”

“We propose a requirement that the expert explains what use of AI has been made other than for transcription (or other administrative uses) and that the expert identifies the AI tools used.”

“draw any appropriate conclusion (including drawing adverse inferences, if appropriate)”

AI in the cases: two lessons

As far as the research for this webinar found, no English or Hong Kong judgment has criticised an expert for using artificial intelligence. The position was checked on 3 October 2026. The two decided cases on the slide come from the United States and from a UK tribunal, and they point in opposite directions.

In Kohls v Ellison (District of Minnesota, 10 January 2025) an academic expert on AI and misinformation used GPT-4o to help draft a declaration. The declaration cited two articles that do not exist and misattributed a third. The court excluded the declaration. It said that it did not fault the expert for using AI for research; the harm comes when lawyers and experts abdicate their independent judgment in favour of ready-made AI answers. The court added that a reasonable inquiry may now require lawyers to ask their witnesses whether they used AI in drafting and what they did to verify the output.

LR (Male VOTs) Albania CG [2026] UKUT 315 (IAC) was decided on 13 August 2026. The Home Office suggested in cross-examination that an academic expert's report had been generated in whole or in part by generative AI. The points relied on were a missed recent report and imperfect English. The Upper Tribunal said that those points, if anything, suggested the report was not written by AI, and that there was no proper foundation for so serious an allegation ([157] to [158]).

The two lessons are practical. Counsel should ask their own expert, before the report is served, whether and how AI was used and how the output was checked, and should keep the answer with the instructions. And counsel should not allege that the other side's expert used AI without a basis. Professional guidance says the same. The Academy of Experts (January 2026) says that experts cannot divest responsibility when they use AI, and that AI is not a substitute for the expert's opinion. An expert should be ready to explain any use of AI under cross-examination. Behind all of this is an older rule: a tribunal will not take an undisclosed method on trust. In Garden House Software Ltd v Marsh [2026] EWHC 2184 (Ch) a valuer relied on a proprietary scoring tool whose workings were never disclosed. The judge said he was in effect asking the court to take a secret methodology on trust ([131]). An AI tool whose use is not disclosed is the same problem.

“But when attorneys and experts abdicate their independent judgment and critical thinking skills in favor of ready-made, AI-generated answers, the quality of our legal profession and the Court's decisional process suffer.”

“We do not consider there to have been any proper foundation for such a serious allegation.”

“now require attorneys to ask their witnesses whether they have used AI in drafting their declarations and what they have done to verify any AI-generated content.”

“None of those points begins to found a suggestion that the Professor used AI to write his report.”

“Experts cannot divest responsibility or evade their duties when they use AI. AI is not a substitute for the expert's opinion.”