Ohio Revised Code Title XXIII. Courts Common Pleas § 2307.23

(A) In determining the percentage of tortious conduct attributable to a party in a tort action under section 2307.22 or sections 2315.32 to 2315.36 of the Revised Code, the court in a nonjury action shall make findings of fact, and the jury in a jury action shall return a general verdict accompanied by answers to interrogatories, that shall specify all of the following:

(B) The sum of the percentages of tortious conduct as determined pursuant to division (A) of this section shall equal one hundred per cent.

(C) For purposes of division (A)(2) of this section, it is an affirmative defense for each party to the tort action from whom the plaintiff seeks recovery in this action that a specific percentage of the tortious conduct that proximately caused the injury or loss to person or property or the wrongful death is attributable to one or more persons from whom the plaintiff does not seek recovery in this action. Any party to the tort action from whom the plaintiff seeks recovery in this action may raise an affirmative defense under this division at any time before the trial of the action.