California Codes, Code of Civil Procedure - CCP, Part 2 — Of Civil Actions, Title 6 — Of the Pleadings in Civil Actions, Chapter 2 — Pleadings Demanding Relief, Article 4 — Cross-Complaints, Section 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.