California Code of Civil Procedure Section 2035

2035.  (a) One who expects to be a party to any action that may be
cognizable in any court of the State of California, whether as a
plaintiff, or as a defendant, or in any other capacity, may obtain
discovery within the scope delimited by Section 2017, and subject to
the restrictions set forth in Section 2019, for the purpose of
perpetuating that party's own testimony or that of another natural
person or organization, or of preserving evidence for use in the
event an action is subsequently filed.  One shall not employ the
procedures of this section for the purpose either of ascertaining the
possible existence of a cause of action or a defense to it, or of
identifying those who might be made parties to an action not yet
filed.
   (b) The methods available for discovery conducted for the purposes
set forth in subdivision (a) are (1) oral and written depositions,
(2) inspections of documents, things, and places, and (3) physical
and mental examinations.
   (c) One who desires to perpetuate testimony or preserve evidence
for the purposes set forth in subdivision (a) shall file a verified
petition in the superior court of the county of the residence of at
least one expected adverse party, or, if no expected adverse party is
a resident of the State of California, in the superior court of a
county where the action or proceeding may be filed.
   (d) The petition shall be titled in the name of the one who
desires the perpetuation of testimony or the preservation of
evidence.  The petition shall set forth all of the following:
   (1) The expectation that the petitioner will be a party to an
action cognizable in a court of the State of California.
   (2) The present inability of the petitioner either to bring that
action or to  cause it to be brought.
   (3) The subject matter of the expected action and the petitioner's
involvement.
   (4) The particular discovery methods described in subdivision (b)
that the petitioner desires to employ.
   (5) The facts that the petitioner desires to establish by the
proposed discovery.
   (6) The reasons for desiring to perpetuate or preserve these facts
before an action has been filed.
   (7) The name or a description of those whom the petitioner expects
to be adverse parties so far as known.
   (8) The name and address of those from whom the discovery is to be
sought.
   (9) The substance of the information expected to be elicited from
each of those from whom discovery is being sought.
   The petition shall request the court to enter an order authorizing
the petitioner to engage in discovery by the described methods for
the purpose of perpetuating the described testimony or preserving the
described evidence.
   (e) The petitioner shall cause service of a notice of the petition
to be made  on each natural person or organization named in the
petition as an expected adverse party.  This service shall be made in
the same manner provided for the service of a summons.  The service
of the notice shall be accompanied by a copy of the petition.  The
notice shall state that the petitioner will apply to the court at a
time and place specified in the notice for the order requested in the
petition.  This service shall be effected at least 20 days prior to
the date specified in the notice for the hearing on the petition.
   If after the exercise of due diligence, the petitioner is unable
to cause service to be made on any expected adverse party named in
the petition, the court in which the petition is filed shall make an
order for service by publication.  If any expected adverse party
served by publication does not appear at the hearing, the court shall
appoint an attorney to represent that party for all purposes,
including the cross-examination of any person whose testimony is
taken by deposition.  The court shall order that the petitioner pay
the reasonable fees and expenses of any attorney so appointed.
   (f) If the court determines that all or part of the discovery
requested may prevent a failure or delay of justice, it shall make an
order authorizing that discovery.  The order shall identify any
witness whose deposition may be taken, and any documents, things, or
places that may be inspected, and any person whose physical or mental
condition may be examined.  Any authorized depositions, inspections,
and physical or mental examinations shall then be conducted in
accordance with the provisions of this article relating to those
methods of discovery in actions that have been filed.
   (g) If a deposition to perpetuate testimony has been taken either
under the provisions of this section, or under comparable provisions
of the laws of another state, or the federal courts, or a foreign
nation, that deposition may be used, in any action involving the same
subject matter that is brought in a court of the State of
California, in accordance with subdivision (u) of Section 2025
against any party, or the successor in interest of any party, named
in the petition as an expected adverse party.