The Common Interest Privilege: An Unsung Ally

Introduction

The common interest privilege can be a useful ally in litigation proceedings or a complex commercial transaction. As its name indicates, it is intended to protect the confidentiality of information exchanged between parties who share a common interest. It can be raised when a person sends a document covered by another privilege to a person with whom the sender has a common interest. Thus, the document in question must initially be covered by either the litigation privilege or professional secrecy in order for the common interest privilege to apply.

The common interest privilege was introduced into English law in 19801 and subsequently introduced and applied in Canadian common law provinces2. It was expressly recognized in Quebec law in the matter of 3312402 Canada inc. v. Accounts Payable Chexs Inc.3 ("Chexs"). The privilege is also applied in connection with commercial transactions, although as we shall see, there was recently some judicial controversy in that regard.

The common interest privilege in Quebec

• The Chexs decision

In Quebec, the Superior Court recognized the application of the common interest privilege in the above-mentioned Chexs decision. Hitherto, the courts had dealt with this privilege indirectly in contexts where another privilege applied or had been waived, but without specifically identifying it4.

In the Chexs case, there were two related files instituted by the same plaintiff against two separate defendants. In one of the files, the plaintiff had asked to examine the lawyer of the defendant in the other file and to obtain a copy of all communications between the two defendants' lawyers. The question the Court had to decide was whether the transmission of privileged documents from one lawyer to the other caused the privilege to be forfeited.

The Court concluded that this common law privilege also applies in Quebec. Regarding the conditions for its application, the court must inquire into the nature of the relationship between the parties in order to ensure that the information or document in question was disclosed on a confidential basis5. It is not necessary that the two parties be represented by the same lawyer6.

The Superior Court concluded that the privilege applied to the communications between the two lawyers in the related files.

• The case law following Chexs

This privilege was subsequently applied in several instances, sometimes specifically by name and other times not.

It has thus been applied...