Cal. Elections Code § 202

Notwithstanding any other law, a person who is deployed on active military service outside of the state and is unable to appear to file a declaration of candidacy, nomination paper, or any other paper necessary to run for office may have that declaration or paper completed and filed by an attorney-in-fact, commissioned and empowered in writing for that purpose through a power of attorney. At the time of filing the declaration or paper, the attorney-in-fact shall present the original power of attorney duly signed by the deployed person. The power of attorney shall state the office that the deployed person is seeking, including the district number, if any, and shall include a declaration that the deployed person meets the statutory and constitutional qualifications for office that he or she is seeking and that if nominated, the deployed person will accept the nomination and will not withdraw. The power of attorney shall further state that the power of attorney is solely for the purpose of authorizing the attorney-in-fact to file a declaration or paper necessary to run for office. The original or a copy of the power of attorney shall be filed with and attached to the declaration or paper.