The 2024 amendments to the Civil Procedure Rules reinforced the court's expectations around the use of ADR. As a result, solicitors now routinely advise clients that refusing to mediate may lead to adverse costs consequences. I recently explored this issue in my article on whether the court can order parties to engage in ADR.
Against that backdrop, the TCC’s decision in MJS Projects (March) Ltd v RPS Consulting Services Ltd [2026] EWHC 884 (TCC) provides a useful reminder that a refusal to mediate will not automatically result in a costs penalty. Whether a refusal to mediate is unreasonable remains highly fact-sensitive and depends on the circumstances of the case.
At its core, this was a professional negligence claim arising out of a construction project.
MJS claimed that flaws in the structural design led to cracking at a container park. RPS, the consulting engineers, disagreed maintaining that the issues were the result of poor workmanship on site.
The case went to trial in April 2025, where the court preferred RPS’s position. The court dismissed the claim and criticised MJS's expert evidence.
The focus then shifted to costs.
The starting point is simple: the losing party usually pays the winner’s legal costs.
MJS accepted that, but argued this was an exception. It said RPS should not recover its costs in full, relying on two main points.
First, MJS argued that RPS had acted unreasonably by refusing to mediate, despite receiving several invitations to do so. In MJS’s view, mediation is a routine step in disputes of this type and could have led to an earlier resolution.
Secondly, MJS argued that RPS introduced additional expert calculations shortly before trial, which it claimed had a significant impact on the outcome. On that basis, it argued it would be unfair for RPS to recover all of its costs.
RPS rejected both points.
It said it hadn’t refused ADR outright, but had taken a careful and practical approach. In particular, it wanted to properly understand MJS’s case - especially the expert evidence - before committing to mediation.
From RPS’s perspective, there were gaps in the information it had been given, particularly around the workmanship allegations. Without that clarity, it said, any mediation would be unlikely to get off the ground.
As for the additional calculations, RPS maintained these were a normal part of dealing with expert evidence in a technical dispute - responding to issues raised by the other side, rather than introducing a new case late in the day.
The court did not accept that RPS's refusal to mediate was unreasonable.
Crucially, it didn’t just focus on the fact that mediation hadn’t happened. Instead, it stepped back and looked at the bigger picture, asking a more practical question:
Was RPS’s overall approach to resolving the dispute unreasonable?
On the facts, the answer was no.
A number of points fed into that conclusion.
The court also considered a common-sense question that often arises in these situations: would mediation have worked anyway?
Here, it thought not.
By that stage, positions were firmly entrenched, the parties had not fully explored the technical issues, and key information was still missing. In those circumstances, mediation was unlikely to resolve the dispute.
Taking all of that into account, the court concluded that RPS had acted reasonably in declining mediation. Given the state of the evidence and the parties' positions at the time, RPS was entitled to conclude that mediation was unlikely to move matters forward.
MJS’s argument about the late calculations didn’t gain traction either.
The judge described the additional calculations as:
“the usual cut and thrust of a professional negligence trial”
In other words, this was normal expert behaviour - testing, checking and responding to the other side’s case. It didn’t amount to a last‑minute change of position and didn’t justify any reduction in costs.
The court ordered MJS to pay RPS's costs and rejected its arguments for any reduction.
For businesses, the message is a practical one.
A refusal to mediate can be justified, but only where there is a proper, defensible reason for doing so. That might include:
What’s risky is a blanket refusal with no explanation. The safest approach remains to engage with ADR where possible. If you choose not to mediate, document your reasoning clearly and make sure it reflects the circumstances of the dispute.
In conclusion, the decision in MJS Projects v RPS demonstrates that a refusal to mediate will not automatically lead to costs sanctions. The court will look closely at the circumstances and decide whether refusing to mediate was a reasonable course of action.
Legal disclaimer The matters contained within this article are intended to be for general information purposes only. This blog does not constitute legal advice, nor is it a complete or authoritative statement of the law in England and Wales and should not be treated as such. Whilst every effort is made to ensure that the information is correct, no warranty, either express or implied, is given as to its’ accuracy, and no liability is accepted for any errors or omissions. Before acting on any of the information contained in this blog, expert advice should always be sought.
© Melissa Worth, June 2026