What can I do on a judgment against me for my ex husband driving a titled car in my name with no insurance?

I take it you didn't have insurance to take care of the lawsuit. If you did, you need to get your car insurance company involved pronto. Hopefully, it won't be too late. If you didn't have insurance, talk to your divorce lawyer about the debt. You may be able to get it addressed in any settlement or verdict. You may also want to consider bankruptcy. If you go down that route, be sure to tell your divorce lawyer.

As the owner of the car, in California, you are liable with the driver for the first $15,000 in damages. So you can not get out of that portion of the judgment. That should have been explained to you by the insurance company, although failure to do so does not void the judgment. You can make the debt part of the divorce decree. His license may very well have been suspended and he is driving without one.

In Michigan there is an Owner Liability Statute that makes the owner liable when their car is permissively used and the negligence of the driver causes damages in a crash. In your circumstances you may have been able to contest the claim if you didn't give your ex permission to use the vehicle, if he stole the vehicle and/or if the Judgment of Divorce awarded the vehicle to him and you signed over the Title. You need to consult a lawyer and/or your divorce lawyer about these, and any other, defenses. However, if you didn't contest the matter when it was brought/pending and you let a Judgment be entered against you, it may well be too late to fix the problem. You should consult counsel to do some research on whether there is a way at this time to "fix" the problem/fight the Judgment. There is a Court Rule that allows you to ask for Relief from Judgment if you do so within 1 year of it being entered.