"Plaintiff" means a person who files a complaint or cross-complaint.
(c) "Related cause of action" means a cause of action which arises out of the same transaction, occurrence, or series of transactions or occurrences as the cause of action which the plaintiff alleges in his complaint.
426.30. (a) Except as otherwise provided by statute, if a party against whom a complaint has been filed and served fails to allege in a cross-complaint any related cause of action which (at the time of serving his answer to the complaint) he has against the plaintiff, such party may not thereafter in any other action assert against the plaintiff the related cause of action not pleaded.
(b) This section does not apply if either of the following are established:
(1) The court in which the action is pending does not have jurisdiction to render a personal judgment against the person who failed to plead the related cause of action.
(2) The person who failed to plead the related cause of action did not file an answer to the complaint against him.
426.40. This article does not apply if any of the following are established:
(a) The cause of action not pleaded requires for its adjudication the presence of additional parties over whom the court cannot acquire jurisdiction.
(b) Both the court in which the action is pending and any other court to which the action is transferrable pursuant to Section 396 are prohibited by the federal or state constitution or by a statute from entertaining the cause of action not pleaded.
(c) At the time the action was commenced, the cause of action not pleaded was the subject of another pending action.
426.50. A party who fails to plead a cause of action subject to the requirements of this article, whether through oversight, inadvertence, mistake, neglect, or other cause, may apply to the court for leave to amend his pleading, or to file a cross-complaint, to assert such cause at any time during the course of the action. The court, after notice to the adverse party, shall grant, upon such terms as may be just to the parties, leave to amend the pleading, or to file the cross-complaint, to assert such cause if the party who failed to plead the cause acted in good faith. This subdivision shall be liberally construed to avoid forfeiture of causes of action.
426.60. (a) This article applies only to civil actions and does not apply to special proceedings.
(b) This article does not apply to actions in the small claims court.
(c) This article does not apply where the only relief sought is a declaration of the rights and duties of the respective parties in an action for declaratory relief under Chapter 8 (commencing with Section 1060) of Title 14 of this part.
426.70. (a) Notwithstanding subdivision (a) of Section 426.60, this article applies to eminent domain proceedings.
(b) The related cause of action may be asserted by cross-complaint in an eminent domain proceeding whether or not the party asserting such cause of action has presented a claim in compliance with Part 3 (commencing with Section 900) of Division 3.6 of Title 1 of the Government Code to the plaintiff in the original eminent domain proceeding.
Article 3. Permissive Joinder of Causes of Action
427.10. (a) A plaintiff who in a complaint, alone or with coplaintiffs, alleges a cause of action against one or more defendants may unite with such cause any other causes which he has either alone or with any coplaintiffs against any of such defendants.
(b) Causes of action may be joined in a cross-complaint in accordance with Sections 428.10 and 428.30.
Article 4. Cross-Complaints
428.10. A party against whom a cause of action has been asserted in a complaint or cross-complaint may file a cross-complaint setting forth either or both of the following:
(a) Any cause of action he has against any of the parties who filed the complaint or cross-complaint against him. Nothing in this subdivision authorizes the filing of a cross-complaint against the plaintiff in an action commenced under Title 7 (commencing with Section 1230.010) of Part 3.
(b) Any cause of action he has against a person alleged to be liable thereon, whether or not such person is already a party to the action, if the cause of action asserted in his cross-complaint (1) arises out of the same transaction, occurrence, or series of transactions or occurrences as the cause brought against him or (2) asserts a claim, right, or interest in the property or controversy which is the subject of the cause brought against him.
428.20. When a person files a cross-complaint as authorized by Section 428.10, he may join any person as a cross-complainant or cross-defendant, whether or not such person is already a party to the action, if, had the cross-complaint been filed as an independent action, the joinder of that party would have been permitted by the statutes governing joinder of parties.
428.30. Where a person files a cross-complaint as authorized by Section 428.10, he may unite with the cause of action asserted in the cross-complaint any other causes of action he has against any of the cross-defendants, other than the plaintiff in an eminent domain proceeding, whether or not such cross-defendant is already a party to the action.
428.40. The cross-complaint shall be a separate document.
428.50. (a) A party shall file a cross-complaint against any of the parties who filed the complaint or cross-complaint against him or her before or at the same time as the answer to the complaint or cross-complaint.
(b) Any other cross-complaint may be filed at any time before the court has set a date for trial.
(c) A party shall obtain leave of court to file any cross-complaint except one filed within the time specified in subdivision (a) or (b). Leave may be granted in the interest of justice at any time during the course of the action.
428.60. A cross-complaint shall be served on each of the parties in an action in the following manner:
(1) If a party has not appeared in the action, a summons upon the cross-complaint shall be issued and served upon him in the same manner as upon commencement of an original action.
(2) If a party has appeared in the action, the cross-complaint shall be served upon his attorney, or upon the party if he has appeared without an attorney, in the manner provided for service of summons or in the manner provided by Chapter 5 (commencing with Section 1010) of Title 14 of Part 2 of this code.
428.70. (a) As used in this section:
(1) "Third-party plaintiff" means a person against whom a cause of action has been asserted in a complaint or cross-complaint, who claims the right to recover all or part of any amounts for which he may be held liable on such cause of action from a third person, and who files a cross-complaint stating such claim as a cause of action against the third person.
(2) "Third-party defendant" means the person who is alleged in a cross-complaint filed by a third-party plaintiff to be liable to the third-party plaintiff if the third-party plaintiff is held liable on the claim against him.
(b) In addition to the other rights and duties a third-party defendant has under this article, he may, at the time he files his answer to the cross-complaint, file as a separate document a special answer alleging against the person who asserted the cause of action against the third-party plaintiff any defenses which the third-party plaintiff has to such cause of action. The special answer shall be served on the third-party plaintiff and on the person who asserted the cause of action against the third-party plaintiff.
428.80. The counterclaim is abolished. Any cause of action that formerly was asserted by a counterclaim shall be asserted by a cross-complaint. Where any statute refers to asserting a cause of action as a counterclaim, such cause shall be asserted as a cross-complaint. The erroneous designation of a pleading as a counterclaim shall not affect its validity, but such pleading shall be deemed to be a cross-complaint.
Article 5. Contents of Documents in Particular Actions or Proceedings
429.30. (a) As