What is the test for admitting evidence beyond the record in a judicial review proceeding?

It is well established that admitting evidence beyond the record in a judicial review proceeding will only be permitted in exceptional circumstances. The general rule is that affidavit evidence which was not before the decision-maker below should not be used to supplement the record on review. There are a few exceptions to that general rule. This Court in Sipekne'katik v. Nova Scotia (Minister of Environment), 2016 NSSC 260 (Sipekne'katik) recently confirmed that these exceptions apply only in “exceptional circumstances.”