Penal Code § 1525
CHAPTER 3. Of Search Warrants
A search warrant cannot be issued but upon probable cause, supported by affidavit, naming or describing the person to be searched or searched for, and particularly describing the property, thing, or things and the place to be searched.
The application shall specify when applicable, that the place to be searched is in the possession or under the control of an attorney, physician, psychotherapist or clergyman.