The leading authority on third-party communications and without prejudice privilege (WPP), Rabin v Mendoza & Co. [1954] 1 WLR 271 (Rabin) has recently been considered by the High Court in two different cases.
Both BNP Paribas Depositary Services Ltd and another v Briggs & Forrester Engineering Services Ltd [2024] EWHC 2575 (BNP v Briggs) and Mornington 2000 LLP (t/a Sterilab Services) v The Secretary of State for Health and Social [2025] EWHC 540 (TCC) (Mornington 2000 v SSHS) dealt with the question of whether a third-party document, unilaterally commissioned by one litigating party in the context of ongoing without prejudice negotiations, would be covered by WPP.
The Judges in each case took a slightly different interpretation of that determined in Rabin.
BNP v Briggs
The Judge commented that it is incorrect to read the Rabin judgment as justifying the application of WPP to third-party communications solely to give effect to an agreement between the parties that they would not seek to rely on those communications at trial. Instead, he observed that Rabin provides that WPP applies to a third-party communication which the parties embark upon jointly as an element of their joint efforts to settle their dispute. In such situations, the third-party communications effectively form part of the negotiations between the parties. In Rabin the third-party report in question did attract WPP because the report would never have come into existence had the parties not jointly decided that it should be obtained by one of them as part of a mechanism that could resolve the dispute.
In BNP v Briggs, third-party reports unilaterally commissioned by the Claimant did not attract WPP because they had been commissioned without a mutual agreement or understanding with the Defendant that they would be used as part of mechanism to progress without prejudice negotiations. It was not sufficient that the Claimants' purpose in commissioning the reports was to assist interparty settlement negotiations.
Mornington 2000 v SSHS
In this case, Rabin was approached as authority for the circumstances in which the ambit of the WPP rule may be widened by the objective agreement between the parties, express or implied.
The question for the court was whether there had been an express or implied agreement that a third-party report, commissioned by the Defendant at a time when the parties were engaged in settlement discussions, was covered by WPP. The Judge held that on the facts, there was no such agreement – the mere fact that interparty without prejudice negotiations referred to the procurement of a third-party report did not mean that there was an express agreement that the report itself should also be 'without prejudice' and thus protected by WPP, nor was there evidence of any implied agreement to the same effect.
Although these cases take slightly differing approaches, they demonstrate the reluctance of the courts to extend the ambit of WPP beyond what is necessary and proportionate for the underlying policy justification that statements made by litigating parties in a genuine attempt to settle should not later be used against them in court. It is a reminder that caution should be exercised when considering unilaterally communicating with a third-party in the context of settlement discussions.
