California Code, Government Code - GOV § 57051

At any time prior to the conclusion of the protest hearing in the notice given by the executive officer, but not thereafter, any owner of land or any registered voter within inhabited territory that is the subject of a proposed change of organization or reorganization, or any owner of land within uninhabited territory that is the subject of a proposed change of organization or reorganization, may file a written protest against the change of organization or reorganization.  Each written protest shall state whether it is made by a landowner or registered voter and shall include the same information that is required in a petition for a change of organization or reorganization, as specified in Section 56704.  Protests may be made on behalf of an owner of land by an agent authorized in writing by the owner to act as agent with respect to that land.  Protests may be made on behalf of a private corporation which is an owner of land by any officer or employee of the corporation without written authorization by the corporation to act as agent in making that protest.

Each written protest shall show the date that each signature was affixed to the protest.  All signatures without a date or bearing a date prior to the date of publication of the notice shall be disregarded for purposes of ascertaining the value of any written protests.