When is leave granted to proceed with a motion?

The law is well-settled on the issue of when leave should be granted to proceed with a motion once a case has been set down for trial. There is no single test for leave pursuant to rule 48.04(1). The relevant principles to be considered and the weight to be given to leave motions will vary depending upon the nature of the leave requested and the circumstances of the case. In the case of routine interlocutory matters that can be raised before the trial judge, for example to amend a pleading, the higher threshold test of substantial and unexpected change in circumstances would apply in order to bring closure to claims in the interests of certainty and predictability. However, where substantive rights are affected, a more flexible test with respect to leave should be applied. In those matters, the merits of the requested relief are a fundamental consideration to ensure the case is fully canvassed at trial, and full consideration must be given to any prejudice to the party opposing the motion that cannot be compensated for by costs. (Tanner v. Clark, [1999] O.J. No. 581, 30 C.P.C. (4th) 358, paras. 9-16)