Cal. Civ. Proc. Code § 2020.210

(a) The clerk of the court in which the action is pending shall issue a deposition subpoena signed and sealed, but otherwise in blank, to a party requesting it, who shall fill it in before service.

(b) Instead of a court-issued deposition subpoena, an attorney of record for any party may sign and issue a deposition subpoena. A deposition subpoena issued under this subdivision need not be sealed. A copy may be served on the nonparty, and the attorney may retain the original.