Tenn. Code Ann. § 31-4-104

When the surviving spouse has been adjudged mentally incompetent as described by title 34, chapters 1-3, or is under the age of eighteen (18) years, at the time the will is admitted to probate, upon a petition filed by a guardian, conservator or next friend of either, within one (1) year from probate, or within any extension period so granted, alleging that it would be to the interest of the survivor to take the survivor's elective share, the court having the proper jurisdiction is empowered to appoint a guardian ad litem and hear proof and to declare or not declare an election, and enter judgment accordingly, subject to appeal.