What is the test for a motion to amend a pleading?

Rule 26.01 provides the on a motion to amend a pleading, the court shall grant leave to amend on such terms as are just unless prejudice would result that could not be compensated for by costs or an adjournment. A pleading will not be permitted where the proposed amendment is not tenable in law, such as an amendment that is frivolous, vexatious or an abuse of process or does not disclose any reasonable cause of action or defence. The onus is on the moving party to show that the claim sought to be added is tenable that law. The responding party bears the onus of showing that the amendment should be denied because it would result in prejudice. See Hartman Estate v. Hartfam Holdings Limited (2006), 200 O.A.C. 369 at para. 25 per Gillese J.A.