Can someone challenge a will during the probate process in Ontario?

Yes. In Ontario, a person who has a legitimate interest in an estate — such as a beneficiary, a dependant, or someone who believes they should have been named — can challenge a will during or after the probate process. Common grounds include lack of testamentary capacity (the testator did not understand what they were signing), undue influence (someone pressured the testator), fraud, or improper execution of the will.

The court notice required before a Certificate of Appointment issues gives potential challengers an opportunity to file a challenge before the certificate is granted. However, challenges can also be brought after probate in certain circumstances.

Will challenges can be lengthy and expensive proceedings. Courts assess evidence about the testator's mental state, the circumstances of signing, and the relationships involved. The person challenging the will generally bears the burden of proving their claim. If successful, the court may invalidate the will entirely or in part, potentially resulting in an earlier valid will or intestacy rules applying.