Here our cross-complaint can be filed by any defendant or cross-defendant. A cross-complainant may assert against plaintiff or cross-complainant any claims, regardless of whether those claims are related to the subject matter of plaintiff’s action. Claims against parties other than plaintiff or cross-complainant must relate to the subject matter or transaction alleged in plaintiff’s complaint. CCP § 428.10.
A cross-complaint is compulsory if the cross-complainant has a cause of action against the party who brought the original complaint or cross-complaint, that “arises out of the same transaction, occurrence, or series of transactions or occurrences as the cause of action alleged by plaintiff in the complaint.” CCP § 426.30(a); CCP § 426.10(c). To qualify as a compulsory cross-complaint, the related cause of action must have existed at the time defendant/cross-complainant served its answer to the complaint. CCP § 426.30(a).
Causes of action that qualify as compulsory cross-complaints are waived if not asserted. CCP § 426.30(a). Qualifications of and exceptions to the waiver rule are found at Code of Civil Procedure § 426 et seq.
A party may seek leave of court to assert an omitted cross-complaint at any time during the pendency of the action. CCP § 426.50.
A party may be joined as a cross-complainant or cross-defendant, if, had the cross-complaint been filed as an independent action, joinder of that party would have been permitted by the statutes governing joinder. CCP § 428.20.
The counterclaim is abolished. Any cause of action that would previously have been asserted in a counterclaim must be asserted in a cross-complaint. CCP § 428.80.
Counter claim is the same as a cross claim.Cross claim is the current terminology here in California.