All About Estates

Common Interest Privilege

Can parties who are on the same side protect privileged communications which are shared among their respective lawyers? 

In some cases, parties may be represented by different lawyers, but have a common interest with respect to a particular issue.  Take, for example, the situation in which a group of estate trustees sued for breach of trust by the beneficiaries are separately represented because they ultimately seek contribution and indemnity against each other.  They nevertheless have a joint interest in claiming over against the solicitor who gave them advice leading to the breach of trust.  The solicitor for one of the estate trustees has done a memorandum of law which he proposes to share with the lawyers for the other estate trustees.  If the memorandum were to be circulated to a stranger to the solicitor and client relationship (i.e. counsel for the other estate trustees), the estate trustee would risk a finding that he has waived solicitor and client privilege.  However, the law allows parties with a common interest to share privileged material among themselves without waiving any privilege that would otherwise attach.

Common interest privilege is not itself a separate category of privilege, but operates to protect privilege from waiver in situations where documents are shared among or between parties.  In Barclays Bank PLC v. Devonshire Trust, Justice Newbould reviewed the law of common interest privilege and found that parties with a common interest could share otherwise privileged material with each other without having waived the privilege.  This was so even though the same parties could ultimately be adverse in interest at some future point.

Another context where this issue may arise for the estate practitioner is on the death of a person who was the subject of a capacity fight.  Say, by way of example, that Child A seeks guardianship over Mom.  Child B and Mom both take the position that Mom is capable.  Child B and Mom are separately represented but their lawyers share information and strategy on the basis of their common interest in a finding of capacity.  Mom dies.  Child A, who is the executor of Mom’s will (and consequently otherwise entitled to waive privilege) seeks to compel Mom’s lawyer to produce privileged documents provided to him by Child B’s lawyer in the guardianship litigation. 

This scenario underscores why it is important, when proceeding on the basis of a common interest privilege, to document the arrangement.  The parties with a joint interest might consider signing an agreement setting out the basis of their common interest and their agreement to maintain confidentiality as against third parties.  They should also consider marking their communications with each other “subject to common interest privilege” so that they can be easily identified and protected. 

Thanks for reading,


About Justin de Vries
Justin has been consistently named as one of the Best Lawyers in Canada/Trusts & Estates. He is an accomplished litigator who has appeared before all levels of the Ontario Court & the Federal Court of Canada. Justin's areas of expertise include: estate, trust, and capacity litigation, as well as probate applications and estate administration. He regularly speaks on estate, trust and capacity issues. Email: