[This post no longer reflects the law and procedure. The Supreme Court Civil Rules were amended effective March 31, 2014 to replace caveats with a "notice of dispute," which you can read about here.]
In British Columbia, our rules permit someone who wishes to dispute the validity of a will to file a document called a caveat in any registry of the Supreme Court of British Columbia. If a caveat is filed, the Court will not grant probate of the will while the caveat is in force.
For example, suppose you were the beneficiary of a will your great-aunt made in 1985. She made a new will in 2005 at a time when she was not functioning well mentally. If you believe that she did not have the mental capacity to make the 2005 will, you can file a caveat in Form 75 of the Supreme Court Rules [as of July 1, 2010, Form 97 of the Supreme Court Civil Rules]. The person your great-aunt named as executor will not be able to immediately obtain a grant of probate.
You must file the caveat before the court has granted probate.
What can the executor do? She may file with the court a notice to caveator in Form 76 [amended to Form 98]. She must then deliver the document to you. You in turn, may file an appearance in Form 7 [Notice of Interest in Form 70]. If you do not file an appearance within the time limit set out in the notice, the caveat will be cancelled.
If you file an appearance to the notice to caveator, the person named as executor in the 2005 will must start a court action to probate the will in solemn form. The executor files the necessary court documents to start a lawsuit, and names as defendants all of those persons with an interest in whether the 2005 will is upheld. You, as someone with an interest in the proceeding, will then have an opportunity to oppose the 2005 will in court.
A caveat expires after 6 months, unless it is renewed.
The relevant rules are Rule 61(34)-(42) [21-5 (41-48)], which oddly enough come under the heading “Administration of Estates (Non-contentious),” as opposed to the heading for Rule 62 [21-4]: “Administration of Estates (Contentious)." Does anyone know why?