Cal. FAC § 31644

If there are no additional instances of the behavior described in Section 31602 within a 36-month period from the date of designation as a potentially dangerous dog, the dog shall be removed from the list of potentially dangerous dogs. The dog may, but is not required to be, removed from the list of potentially dangerous dogs prior to the expiration of the 36-month period if the owner or keeper of the dog demonstrates to the animal control department that changes in circumstances or measures taken by the owner or keeper, such as training of the dog, have mitigated the risk to the public safety.