Ohio Rev. Code § 5817.09: Burden of proof.

(A) The testator or settlor has the burden of establishing prima facie proof of the execution of the will or trust, as applicable. A person who opposes the complaint has the burden of establishing one or more of the following:

(1) The lack of testamentary intent or the intent to create a trust, as the case may be;

(2) The lack of the testator's testamentary capacity, or the settlor's legal capacity to enter into and establish the trust;

(3) Undue influence, restraint, or duress on the testator or settlor;

(4) Fraud or mistake in the execution of the will or trust;

(5) Revocation of the will or trust.

(B) A party to the proceeding has the ultimate burden of persuasion as to the matters for which the party has the initial burden of proof.