Ohio Rev. Code § 4510.04: Affirmative defenses to driving under suspension or cancellation.

It is an affirmative defense to any prosecution brought under section 4510.037, 4510.11, 4510.111, 4510.14, 4510.16, or 4510.21 of the Revised Code or under any substantially equivalent municipal ordinance that the alleged offender drove under suspension, without a valid permit or driver's or commercial driver's license, or in violation of a restriction because of a substantial emergency, and because no other person was reasonably available to drive in response to the emergency.