California Code, Code of Civil Procedure - CCP § 410.30

(a) When a court upon motion of a party or its own motion finds that in the interest of substantial justice an action should be heard in a forum outside this state, the court shall stay or dismiss the action in whole or in part on any conditions that may be just.

(b) The provisions of Section 418.10 do not apply to a motion to stay or dismiss the action by a defendant who has made a general appearance.