Mediation Privilege – What is it and should we have it?

David Watkinson reflects on the reality of whether mediation privilege exists, and the differences between confidentiality and ‘without prejudice’, in the context of negotiations.

Introduction

All mediators are familiar with the principle that what is said or done in the course of a mediation stays in the mediation. Any body involved in a mediation process will very soon be informed that what happens during it is confidential, that it cannot be disclosed to any other person not involved in the mediation process itself.

Even within the process, what is said or provided to the mediator by any party in private session cannot be passed on to another party without consent. In particular, concessions or offers made cannot be referred to afterwards in any subsequent legal proceedings. All this is to enable the parties to negotiate freely and (hopefully) successfully.

Parallels have been drawn with the privilege attached to “without prejudice” negotiations which prevents their disclosure.

For about the last decade, the question has been asked, especially in mediation circles, whether there is emerging, or should be, a distinct “mediation privilege”. This has been given added impetus by increasing references to the concept in case law. Additionally, the anticipated effect of Churchill v Merthyr Tydfil CBC [2023] EWCA Civ 1416. Subsequent additions to the CPR leading to more mediations taking place or encouragement to by an order of the court.

This blog therefore asks the following questions (and attempts to answer them).

• (1) Does mediation privilege exist?
• (2) If not, should it?
• (3) If so, what should it cover?
• (4) How can it come into existence?

Does mediation privilege exist?

The short answer to this question is NO. For it, I am much indebted to the lecture “No Mediation Privilege Yet” given on 10th December 2025 by Michael Kallipetis KC. This is the first CMC Academic lecture hosted by the Centre for Dispute Resolution at UCL. This must, surely, be the most comprehensive consideration of the relevant case-law currently in existence. The position is succinctly put by HHJ Tindal (sitting as High Court Judge) in Pentagon Fuel Group v B. Cadman Ltd [2024] EWHC 2513 thus, “The authorities do not support the view that “mediation privilege” is distinct from “without prejudice privilege” para 60).

And, with some wobbles, that is the burden of the case-law. While both “mediation privilege” and “without prejudice privilege” are referred to, suggesting some distinction, what it comes down to is that they are equated. See, for example, Cumbria Waste Management v Baines Wilson [2008] EWHC 786, HHJ Frances Kirkham (sitting as a High Court Judge) and Ferster v F [2016] EWCA Civ 717).

And there is the sting in the tail. Because “without prejudice privilege” is subject to judge-made exceptions. They are well known.

Statements made on a “without prejudice” basis can be admissible:

• (1) to show an agreement was reached
• (2) to show that an agreement should be set aside because it was obtained by fraud, misrepresentation or undue influence
• (3) to provide evidence of an estoppel
• (4) to expose perjury, blackmail or clear impropriety
• (5) to explain delay in pursuing a claim (Unilever v Proctor and Gamble [2000] WLR 2436 @ 2444A-5G Walker LJ).  And the same exceptions have therefore been said to apply to mediation privilege.

Should there be a specific mediation privilege?

Which is independent and distinct from “without prejudice” privilege.

This writer proposes there should be. The reasons are:-

• (a) The mediation process itself is distinct from the “without prejudice” negotiations process. Obviously, it no longer involves two or more parties’ representatives negotiating on behalf of clients and seeking to protect clients’ interests. It involves an impartial third party (the mediator), whose role is to assist the parties to settle their dispute.
  • An important part of that process is the receipt of information in confidence from each party, not communicable to the other(s) without consent. This enables the mediator, for example, to gauge how to approach each in furtherance of a resolution.
  • As Kallipetis points out, such candour between the mediator and the parties is unlikely to occur if they are aware that what is said in confidence can become evidence in the court room or more widely known.
• (b) Confidentiality can be and usually is dealt with by contract. That is, the Mediation Agreement signed by the parties, representatives and those attending the mediation, as well as the mediator. As we have seen with “without prejudice” privilege, what the parties believed to have been kept secret can be revealed by court (or statute) imposed exceptions.
  • For the sake of clarity, therefore mediation privilege should be defined by law together with any exceptions to it.
• (c) This has become even more relevant as an issue following the Churchill decision and the subsequent amendments to the Civil Procedure Rules. See my blog “Mandatory Mediation – The Rules They Are A-Changing” November 25th 2024. Now that the court can order parties to mediate (or “encourage to engage” in mediation), it may be anticipated the number of mediations will increase with one or other of the parties not being wholly willing.
  • As was suggested at the recent CMC conference (12-13 November 2025), suppose one party wishes to raise the failure of the other to “engage” at the mediation (e.g. by refusing to take part or doing so but in an obstructive manner). How can that be done without breaching the principle of the confidentiality of the mediation?
  • It is worth noting that if it has been held in a costs issue, the court can receive evidence of unreasonable behaviour by one party which might have caused the mediation to fail. This being equivalent to unreasonably refusing to mediate at all (Jack J in 7th Earl of Malmesbury v Strutt & Parker [2008] 5 Costs LR 736.
• (d) Finally, the transactions that take place about the mediation, between the parties themselves and also with the mediator present, should be confidential on the same basis, as without prejudice negotiations, so that the parties can freely express themselves, make offers and concessions for the purpose of settlement without such statements being used at trial.

If there is mediation privilege, of what should it consist?

It is suggested the starting point should be a requirement of confidentiality for all transactions between the parties and the mediator, before, at and after the mediation, in connection with the dispute. As Kallipetis suggests, exceptions can then be added.

For example, it is suggested that the without prejudice exceptions should apply and anticipated that this would not be controversial.

Kallipetis adds that the privilege should not apply to whatever disclosure is necessary to enable enforcement or implementation of the concluded agreement. Normally, the agreement itself would be sufficient. This, too, would seem to be non-controversial.

He adds “public policy” exceptions. These would be limited to:

• (1) securing or protecting children’s best interests
• (2) preventing harm to the physical or psychological integrity of a person
• (3) the prevention of crime
• (4) safeguarding national security

Presumably, whether these applied would be a matter of discretion for the judge to decide.

Finally, recognising that an exception permitting examination of a party’s conduct during the mediation may be opening a hornet’s nest. Nevertheless, this writer proposes that that there be an exception, enabling a party’s alleged refusal to engage during a mediation. For example, by refusing to take part or by obstructing the process) to be investigated by the court. Usually, this would arise when a costs issue is raised. Otherwise, the judgment in Churchill could be undermined.

How can mediation privilege come into existence?

There are only two ways. By judicial determination or by statute. It is anticipated that judicial determination is the more likely as the courts are already becoming familiar with the term. Although this means that the exceptions are likely to be added piecemeal. The alternative is a Mediation Act (New Zealand, Ireland and some US States show the way). And who is going to propose that?