“Where the court concludes that success was divided, it may award costs to the party who was more successful on an overall global basis or on the primary issue, subject to adjustments that it considers appropriate, having regard for the lack of success on secondary issues and any other factors relating to the litigation history of the case (Gomez-Pound v. Pound, [2009] O.J. No. 4161 (O.C.J.); Boland v. Boland, 2012 ONCJ 239 (CanLII), [2012] O.J. No. 1830 (O.C.J.)).
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The court must step back and exercise a judgment, having regard to all the circumstances as to what a fair and reasonable amount should be paid by the unsuccessful party rather than any exact measure of the actual costs to the successful litigant is. See: Boucher v. Public Accountants Council for the Province of Ontario, 2004 CanLII 14579 (ON C.A.), (2004) 71 O.R. (3d) 291 (C.A.)
The ultimate costs determination must reflect proportionality to the issues argued. There should be a correlation between legal fees incurred for which reimbursement is sought and the importance or monetary value of the issues at stake. The rules do not require the court to allow the successful party to demand a blank cheque for their costs. See: O’Brien v. O’Brien, 2017 ONSC 402 (CanLII).”