Refusing to Mediate – Further TCC Guidance on Costs in Professional Negligence Claims

In MJS Projects (March) Limited v RPS Consulting Services Limited [2026] EWHC 884 (TCC)¹, the Technology and Construction Court refused to depart from the usual costs order following the dismissal of a professional negligence claim against consulting engineers. The claimant (MJS) had argued that RPS should be deprived of its costs due to an alleged unreasonable failure to mediate and because of alleged late changes to its expert’s evidence. The Judge rejected these arguments, ordering MJS to pay RPS’s costs and granting payment on account. The judgment offers guidance for construction professionals and their insurers on alternative dispute resolution (ADR) conduct, expert evidence and the applicable threshold for costs sanctions.

Background

The underlying substantive claim concerned alleged negligent design and construction of a container park². MJS alleged that defects in RPS’s structural design caused cracking on site. RPS denied negligence, contending that the damage was instead caused by workmanship defects.

Following trial, the claim was dismissed in April 2025, with the Court criticising MJS’s expert evidence and accepting that workmanship caused the damage. The recent judgment dealt with costs and consequential issues.

MJS accepted that the usual order would be that costs follow the event. However, MJS sought to depart from this rule – seeking no order as to costs be made – relying upon what it alleged to be (i) RPS’s unreasonable refusal to mediate and (ii) an alleged last‑minute change in RPS’s expert’s position concerning evidence on the mass concrete taper and supporting calculations.

RPS sought its costs in full.

The parties’ positions

MJS asserted that RPS had unreasonably and repeatedly failed to engage in mediation despite invitations pre‑action and during proceedings. It argued mediation is routine in professional negligence claims and would have had a reasonable prospect of resulting in settlement. MJS characterised RPS’s objections and reasons for refusal as shifting over time and submitted that the technical nature of the dispute was no barrier to ADR.

MJS also pointed to RPS’s expert’s assumptions being supplemented by late calculations served shortly before trial. MJS indicated that this had a decisive effect on the outcome of the trial and so justified depriving RPS of its costs.

Conversely, RPS’s position on its conduct was that it had not refused ADR unreasonably but had consistently sought to understand MJS’s expert case first. RPS pointed to years of unaddressed allegations of workmanship defects, MJS’s failure to engage with these issues or share expert evidence (even on a without prejudice basis) and pointed to settlement attempts through offers that were made.

On receipt of the defendant’s witness statement dealing with why mediation was not previously agreed to, MJS indicated it would be prepared to mediate but only on two identified dates and on restricted terms, including that RPS would have no say in the identity of the appointed mediator. RPS disagreed that those terms were appropriate to enable constructive mediation and made another Calderbank offer instead.

RPS also argued that the additional calculations were routine ‘check’ work responding to criticisms from MJS’s expert and caused no prejudice or additional cost.

Decision

MJS was ordered to pay RPS’s costs. In summary, the Court reaffirmed that mediation is only one form of ADR. While RPS had declined mediation, that stance was not unreasonable in the context. RPS repeatedly sought clarity on MJS’s expert evidence and workmanship allegations, which was reasonably required before meaningful mediation could occur. MJS’s failure to engage with those issues, coupled with late and restrictive mediation proposals close to trial, weighed against any costs sanction.

The Court held that mediation would not have had a reasonable prospect of success on the facts given the parties’ entrenched positions, lack of shared expert understanding, and MJS’s refusal to provide key information.

Concerning the expert evidence, the Judge acknowledged the additional calculations were “simply part of the usual cut and thrust of a professional negligence trial” and “sense check testing” expected from an expert³. Although RPS’s expert provided additional evidence on one point, that issue was not central to RPS’s pleaded case and had no material bearing on liability or costs.

RPS was awarded an interim payment on account of costs of approximately £310,000 plus interest.

Key takeaways

This judgment will interest construction professionals and PI insurers for various reasons. Firstly, it provides practical reassurance that a clearly documented and reasoned refusal to mediate will not automatically attract a costs penalty despite recent case law demonstrating the drive towards effective ADR processes. The Court considered the parties’ conduct holistically, including pre‑action engagement, information asymmetry and alternative settlement attempts. Requiring sight of expert evidence before mediation was not unreasonable in a technically driven dispute of this nature.

Second, the decision highlights the importance of expert instruction. The criticisms of the claimant’s expert in the underlying action were clear and determinative. Insured businesses and insurers should take note of the risks associated with unclear or inadequate expert methodology, failure to address pleaded issues and late or uncommunicated changes to analysis or evidence.

Beale & Co have experience on advising on professional indemnity matters and disputes. If you wish to discuss the items covered in this article or understand how these apply to your projects, please contact Callum Young or your usual Beale & Co contact.

¹MJS Projects (March) Ltd v RPS Consulting Services Ltd [2026] EWHC 884 (TCC) (15 April 2026)

²The earlier substantive judgment can be found using citation [2025] EWHC 831 (TCC).

³Judgment, paragraph 55