Can a writ of mandate be issued to vacate an order preventing a plaintiff from suing her insurance company while a third party action is pending?

This is an appropriate case for issuance of a writ. "[W]here an order bars a substantial portion of a plaintiff's case from being heard on the merits, a petition for writ of mandate to vacate that order may be maintained." (Nazaroff v. Superior Court (1978) 80 Cal.App.3d 553, 557-558, 145 Cal.Rptr. 657.) Further, this case, which is one of first impression on the issue of whether an insured may sue its insurance company while a third party action is pending, is one of sufficient general interest to the public and to the bar to warrant an immediate decision.