If a court finds part of a will valid and part invalid, how are the litigation costs sorted out?

Where an Ontario court finds that part of a will is valid and severs out only the invalid portion — for example, a clause procured by undue influence, while the rest of the will properly reflects the testator's intentions — costs are generally decided based on how the litigation was actually conducted and who succeeded on which issues, rather than following a single automatic rule. A split result on the merits often leads to a split, or at least a more nuanced, costs outcome.

In practice, courts commonly look at whether each side succeeded on the issues they pursued, whether the challenge that led to severance was reasonably brought given the deceased's own conduct or the circumstances of the will's preparation, and whether either side ran up unnecessary costs pursuing points they ultimately lost. It's common in a partial-success case for each party to bear their own costs, for costs to be apportioned between the parties reflecting the mixed result, or for a portion of costs to be paid from the estate, particularly for costs connected to the part of the will that was reasonably found invalid. Because outcomes vary significantly with the specific facts, get advice on likely costs exposure as the case develops, not just at the outset.