If you and another person have shared ownership of a car and the other person let's the registration expire are you still legaly bound to the car in anyway?

I put a car in my name along with my nieces name on the title transfer. The car was for and she recently stated that the car was no longer registered. She still drives it, so if anything were to happen would I have to be contacted or have to pay for any legal expenses since the car is no longer registered?