Why do losing parties sometimes avoid paying costs in an Ontario will challenge?

Estate litigation follows a different costs tradition than most other civil disputes. In ordinary lawsuits, the losing side typically pays a portion of the winner's legal costs, but Ontario courts have long recognized that will challenges can raise a genuine public interest in making sure a will is valid, especially where the circumstances that led to the challenge — such as the testator's capacity or the conduct of someone involved in preparing the will — were reasonably put in question by the deceased's own conduct or the situation itself, not manufactured by the person who lost.

Where a court finds the losing party had reasonable and probable grounds to bring or defend the challenge, and the need for investigation arose from how the testator or others behaved rather than from the losing party's own conduct, it has discretion to order that the party's costs be paid from the estate, or to make no costs order against them at all, rather than making them personally responsible for the other side's costs. This isn't automatic, though — modern Ontario courts have moved toward applying ordinary costs principles more often in estate cases than in the past, especially where a challenge appears to have been unreasonable or driven by personal grievance rather than a genuine concern about validity.