Can a spouse take out an auto loan and place her husband as the primary in the State of Illinois?

"Fruit of the  poisonous tree" deals with evidence which has been derived from other evidence which was improperly obtained. I don't completely understand your question because you can't be liable on a contract to which you, or someone acting on your behalf, did not agree, e.g. sign.  When you say that you are the "primary", do you mean the primary driver (which wouldn't make you responsible for the loan) or the primary borrower, which your wife oculdn't do legally without your permission.  So either your wife signed on your behalf as your agent, or she forged your signature.  If so, and the dealership knew that your wife didn't have authority to act for you and/or knew about the forgery, you are not liable on the loan.  If the dealership did not know, you may still be lieble, but can sue your wife for any payments you have to make.  Practically, of course, the right to sue your wife is probably not worth much, especially because if she had the money to pay you she would presumably have paid the loan in the first place. Another major practical problem is that if you, knowing about this issue, don't promptly complain and inform the dealership that you never agreed to this and your wife had no authority to agree for you, you may be deemed to have ratified the agreement and become liable.  On the other hand, if you do complain, you may get your wife in serious trouble, including with the police. Another issue is that the loan may have been assigned to a party who had no reason to know of any problems with it, in which case you could still be liable on it, although again you could sue your wife (and also the lender, if it knew about the issue).