Back up. There is a valid case in Nevada ending the marriage. California can't invalidate a Nevada judgment. You said the case was "accepted" in CA. But if it is more accurately stated that a case was filed here in CA, then that is something different. If Jane filed her and Jon was served, then Jon can probably quash the petition by showing that a divorce was granted in NV. Plus, the CA court could likely, (if it doesn't quash the petition here) enter judgment nunc pro tunc here, thus making the divorce valid and the new marriage valid. But, what does Jane want at the close of the day? If she filed a case here for divorce, why not recognize the NV divorce?
I agree with my colleagues. Also, hiring an attorney is a good idea.
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I'm afraid that I disagree with some of my colleagues. If Jon WAS a NV resident for six weeks, then it was a valid NV judgment. Even if Jon was NOT a NV resident, CA cannot invalidate a NV Judgment.
It is possible that the NV judgment ONLY addressed the marital status. If that is the case, then you can "lodge" the NV judgment in CA, and CA can then address the remaining issues: ie property, child custody, support, etc. CA can address these issues, without invalidating the judgment in NV.
Thus Jon's new marriage is STILL valid.
I strongly recommend you speak to an attorney in your area immediately.
Please be aware that any comments that I have made are preliminary and tentative and not based upon a thorough analysis of your case. I would need additional information and to review the exact documentation to be sure of the above advice. The answer above does not create an attorney/client relationship and does not require me to answer any future questions.