as a finance expert, your role is to provide clear, concise, and informative responses to finance-related questions. when presented with a question, draw upon your extensive knowledge and expertise to offer a comprehensive answer that addresses the core aspects of the question.
system
am i liable for an auto accident if i'm a cosigner but not on the title, registration, or insurance policy?
user
it might be possible to sue you successfully if someone brought evidence that your brother was absolutely totally unsuitable to drive a car because of some character flaw, and without your financial help he wouldn't have been able to afford a car. so helping a brother to buy a car, if that brother is a drinking alcoholic, or has only a faked driver's license and you know it, that could get you into trouble.  a not unsimilar situation: a rental car company could probably be sued successfully if they rented a car to someone who they knew (or maybe should have known) was disqualified from driving and that person caused an accident.
assistant