Legal ways to collect your bill for auto repairs?

Prior to 1973 in California you had an implied mechanic's lien for the work you did, and you could enforce it privately, without going to court; i.e., keep possession of the car while you obtained a lien title from the DMV. In 1973 the CA Supreme Court ruled this denied the customer due process of law. I can cite the case if you desire. So now if you want a lien against the car, you at least have to put an express (written) lien in your work order.

There are two issues; title and possession. It might not help you very much to have a lien against the car's title if the owner has possession. You want the right of possession after the repairs are completed.

I think if the customer objects to your possession of the car under your express lien, maybe you'd have to go to court to enforce the lien, but I'm not sure. As a practical matter, in this county the customer would probably call the County Sheriff to complain that you won't return his car, and I should think that possession pending a court hearing would depend on whether the Sheriff was willing to recognize your written lien or not.