Legal Question in Personal Injury in Indiana

No, that has nothing to do with your negligence.

Unfortuantely for you in this circumstance, whether or not the license plate of the other driver was current or not, will not have any bearing on the determination of who was at fault. The expired plate is only an issue between that party and the State of Indiana. The person may be fined or otherwise punished for having expired plates, but that will not change the determination about who was at fault. You should, if you haven't, notify your own insurance company of the accident promptly. Your insurer will provide you with a lawyer for the defense of the claim at no expense to you and either settle or defend the case against you.