Ohio Rev. Code § 2943.05: Form of plea of former conviction.

If a defendant pleads that he has had former judgment of conviction or acquittal, or has been once in jeopardy, he must set forth in his plea the court, time, and place of such conviction, acquittal, or jeopardy. No claim of former judgment of conviction or acquittal, or jeopardy may be given in evidence under the plea of not guilty.