California Code, Probate Code - PROB § 5696

(a) Nothing in this chapter limits the application of principles of fraud, undue influence, duress, mistake, or other invalidating cause to a transfer of property by a revocable transfer on death deed.

(b) Notwithstanding subdivision (a) of Section 5692, the conservator or guardian of a transferor may, before the transferor's death, petition the court for invalidation of a revocable transfer on death deed executed by the transferor.