True, but you can only sue for actual damages... which in this case would be whatever amount he agreed to pay. (rent, utilities, etc.) Since this agreement was between him and his roommate which he had no legal right to have in the first place, there may not even be any "damages". ORC 5321.14
states: (A) If the court as a matter of law finds a rental agreement, or any clause thereof, to have been unconscionable at the time it was made, it may refuse to enforce the rental agreement or it may enforce the remainder of the rental agreement without the unconscionable clause, or it may so limit the application of any unconscionable clause as to avoid any unconscionable result.
Disclaimer: This is not legal advice. Anything that may be misconstrued as legal advice I accept no responsibility for. I am a font of useless knowledge, usually obtained through getting myself in a lot of shit, and having an attorney as a good friend. I am not qualified to advise or represent you on any legal matter; however, if you need spark plugs, brake pads, or automotive project advice, I'm your man.