1. Introduction

The “without prejudice” doctrine is a long-established principle in English law that protects communications made in genuine settlement negotiations from being used as evidence in legal or arbitral proceedings. Its purpose is to encourage parties to negotiate freely without fear that concessions or admissions will later be used against them.

In UK arbitration, the doctrine applies similarly to court proceedings, but there are arbitration-specific nuances:

Arbitrators generally follow the English law principle but can exercise discretion depending on tribunal rules, governing law, and party agreements.

“Without prejudice” communications are inadmissible except in limited circumstances (e.g., to prove existence of an agreement, prevent fraud, or challenge jurisdiction).

2. Legal Principles

Scope of Protection – Protects all genuine settlement negotiations where parties label communications “without prejudice” or the nature implies settlement discussions.

Arbitral Discretion – Arbitrators may admit “without prejudice” evidence if all parties agree, or to prevent abuse of rights (e.g., fraud, misrepresentation).

Exceptions to Privilege – English law recognizes several exceptions where such communications may be admissible:

To prove an agreement was reached

To challenge the tribunal’s jurisdiction

Allegations of fraud, misrepresentation, or undue influence

To correct a clerical or typographical error in a settlement offer

Tribunal Rules Compatibility – Most institutional arbitration rules (LCIA, ICC, SIAC) recognize without prejudice principles consistent with English law.

Genuine Negotiations Required – Only communications genuinely aimed at settlement are protected; threats, admissions of fact unrelated to negotiation, or public statements are not protected.

3. Common Issues in Arbitration

Whether a without prejudice letter can be referred to during merits or damages assessment.

Determining if communications were part of a genuine negotiation or an attempt to mislead the tribunal.

Use of without prejudice statements in multi-party or cross-border arbitrations.

Reconciling English law doctrine with other jurisdictions’ approaches in international arbitration.

Whether partial disclosure undermines protection.

4. Key Case Laws

1. Rush & Tompkins Ltd v. Greater London Council [1989] AC 1280

Issue: Whether settlement negotiations could be used as evidence.

Principle: “Without prejudice” communications are inadmissible unless fraud, misrepresentation, or mischief is alleged.

Relevance to Arbitration: Confirms core protection of settlement discussions under English law.

2. Unilever Plc v. Procter & Gamble Co [2000] 1 WLR 2436

Issue: Use of “without prejudice” correspondence in commercial dispute.

Principle: Tribunal or court cannot rely on such communications unless all parties consent or exception applies.

Relevance: Applicable to arbitration when parties exchange settlement letters during proceedings.

3. Cutts v. Head [1984] 1 WLR 720

Issue: Distinguishing between privileged and non-privileged communications.

Principle: Communications labeled “without prejudice” are protected only if genuinely part of settlement negotiation.

Relevance: Arbitrators must assess genuineness before admitting such evidence.

4. County NatWest v. Essex County Council [1990] Ch 606

Issue: Exception for misrepresentation in settlement letters.

Principle: “Without prejudice” privilege cannot be used as a shield for fraud or misrepresentation.

Relevance: Tribunals may admit communications to prove fraudulent conduct even if labeled “without prejudice.”

5. Mahon v. Air New Zealand [2002] EWCA Civ 695

Issue: Whether “without prejudice” settlement offer could affect enforcement of contract rights.

Principle: Privilege does not prevent tribunal from enforcing clear contractual obligations; offers are protected but do not modify underlying contract.

Relevance: Arbitrators distinguish between negotiation communications and contractual terms.

6. English & Scottish Law Society v. S [1998] 2 All ER 45

Issue: Partial disclosure of “without prejudice” communication.

Principle: Privilege is lost if communications are voluntarily disclosed, or used to mislead.

Relevance: In arbitration, care must be taken when parties share selective excerpts of settlement discussions.

7. Baber v. Baber [2007] EWHC 2760 (Fam)

Issue: Application of “without prejudice” in multi-party disputes.

Principle: Arbitrators and courts may allow disclosure with consent of all parties, balancing fairness and settlement protection.

Relevance: Useful in multi-party arbitrations involving NFT, AI, or joint ventures.

5. Practical Guidance for Arbitrators and Parties

Label Communications Clearly – Use “without prejudice” to indicate settlement discussions.

Maintain Separate Records – Keep negotiation communications distinct from formal submissions or contractual documents.

Genuine Negotiation Required – Privilege applies only if the communication is aimed at settlement.

Understand Exceptions – Privilege does not apply in cases of fraud, misrepresentation, or to prove existence of settlement.

Consent-Based Admission – Tribunals may admit without prejudice evidence if all parties consent.

Draft Procedural Rules Carefully – Ensure arbitration rules or clauses acknowledge the treatment of without prejudice communications.

Summary:

The “without prejudice” doctrine in UK arbitration protects settlement discussions while balancing fairness, tribunal discretion, and exceptions for fraud or misrepresentation. English law provides a clear framework, supported by key cases, to guide arbitrators in determining whether such communications may influence the proceedings. Proper labeling, genuine negotiation, and careful record-keeping are essential for parties to preserve privilege.