rental car fee, help please!

My car was hit by somebody, He did not have insurance. he agreed to pay the repair but refused to pay the rental car fee. he told me" I am not going to pay it , you can go ahead suit me, it will cost you $400 lawyers' fee). my question is if he has insurance, I believe insurance will cover my rental car fee, but if he don't have insurance, is he responsible(by law) to pay the rental car?

thanks