A recent High Court decision confirms that where a party relies on the contents of privileged material to support its case on the merits at the interlocutory stage, it will be taken to have waived privilege in the relevant materials for the purposes of the trial: Berezovsky v Abramovich  EWHC 1143. As the judge commented, parties to litigation cannot adopt a "now you see it, now you don't" approach to deploying privileged material.
In this case, in defending a summary judgment application, the claimant had relied on parts of privileged interviews between his former solicitors and his former business associate, Mr Patarkatsishvili (who had since died). The defendant then applied for disclosure of all documents in the claimant's control recording or reflecting the contents of the relevant interviews, arguing that since the claimant had deployed part of the communications in relation to the merits of his claim, he had thereby waived privilege in all documents relating to the same subject matter (under the principle of collateral waiver).
The court granted the application, rejecting the claimant's argument that there had merely been a limited waiver for the limited purpose of the summary judgment application. The court held that it was bound by the Court of Appeal decision in Dunlop Slazenger International Ltd v Joe Bloggs Sports Ltd  EWCA Civ 901 to find that where, as here, there has been deployment of privileged material in interlocutory proceedings to support a party's case on the merits, it is then too late for the deploying party to attempt to turn the clock back. It makes no difference whether the deploying party has yet made up its mind whether to deploy the same material at trial