This Application arose in the context of complex litigation over a pipeline failure. CNOOC Petroleum North America ULC (“CNOOC”), the Plaintiff, had answered Undertakings about whether a pipeline integrity management program applied to the corridor pipelines in 2014-2015. Certain Defendants, Sunstone Projects Ltd and Wood Group Canada, Inc (collectively, the “Wood Group”), applied for a correcting Affidavit under Rule 5.27(2) after CNOOC later revised its Undertaking responses.

The Court set out the Rule 5.27 framework. A witness who has been questioned must correct any answer that was incorrect or misleading, or that becomes incorrect or misleading by Affidavit and serve it as soon as practicable. Endorsing the rationale in Signalta Resources Limited v Canadian Natural Resources Limited, 2021 ABQB 867, Nixon A.C.J. emphasized that the correcting Affidavit safeguarded sworn evidence, prevented trial ambush, and enabled cross-examination on why and how the evidence changed.

The Court then clarified what a compliant correcting Affidavit must contain. It need not catalogue every internal step, but it must provide enough substance to permit meaningful cross-examination. At a minimum, it should explain what changes have been made, what led to the correction, and how the change corrected the earlier evidence. A narrative of procedural back-and-forth, without those core explanations, is insufficient.

Applying these principles, Nixon A.C.J. held that CNOOC’s correcting Affidavit did not meet Rule 5.27(2) for the amended responses to two Undertakings. The Affidavit largely recited the history of requests and responses and pointed to a document already in disclosure. However, it did not explain why the prior answers were wrong or misleading, why the newly cited document mattered now, or how the revisions corrected the record. By contrast, no correcting Affidavit was required for two other Undertakings because those answers were not amended.

In the end, the Court directed CNOOC to serve a new correcting Affidavit that satisfied Rule 5.27(2) by addressing what changed, what led to the change, and how the change corrected the evidence.