​The Federal Court of Appeal in IGGillis Holdings Inc. v. Canada (National Revenue) has ended the uncertainty it had created in previous decisions which suggested that common interest privilege did not exist as between parties to a transaction. The doctrine of common interest privilege provides that where parties with a common interest (e.g. co-defendants aligned in interest) share privileged information, they do not waive the privilege over the information. The law in Canada was recently unsettled as to whether, in the context of a transaction where parties share privileged information relating to the transaction or to one party, the parties will have waived privilege by sharing the information with the transactional counterparty. Previous decisions of the Federal Court had suggested that transactional common interest privilege had been weakened in Canadian law, but this decision has ended the uncertainty surrounding the ability to share privileged communications with other parties to a transaction, and reaffirmed the status of transactional common interest privilege as "strongly implanted in Canadian law".

However, the decision does not eliminate the need for caution in the disclosure of privileged materials, but confirms that with sufficient intention of confidentiality and common interest, privilege may be maintained.