Ohio Revised Code Title XXVII. Courts Revised Code General Provisions Special Remedies § 2743.43

(1) Such person is licensed to practice medicine and surgery, osteopathic medicine and surgery, or podiatric medicine and surgery by the state medical board or by the licensing authority of any state;

(2) Such person devotes three-fourths of the person's professional time to the active clinical practice of medicine or surgery, osteopathic medicine and surgery, or podiatric medicine and surgery, or to its instruction in an accredited university;

(3) The person practices in the same or a substantially similar specialty as the defendant. The court shall not permit an expert in one medical specialty to testify against a health care provider in another medical specialty unless the expert shows both that the standards of care and practice in the two specialties are similar and that the expert has substantial familiarity between the specialties.

(4) If the person is certified in a specialty, the person must be certified by a board recognized by the American board of medical specialties or the American board of osteopathic specialties in a specialty having acknowledged expertise and training directly related to the particular health care matter at issue.