Ohio Rev. Code § 3902.31: Void contracts.

(A) As used in this section:

(1) "Pay in full" means paying for a health service in its entirety without cost-sharing on the part of a third-party payer. "Pay in full" includes payment made under a deductible requirement.

(2) "Third-party payer" and "provider" have the same meanings as in section 3901.38 of the Revised Code.

(B)(1) Subject to division (C) of this section, a provision in a contract entered into between a third-party payer and a provider is void and against public policy if it does either of the following:

(a) Establishes a minimum amount that the provider is required to charge an individual for a health service when that individual pays in full for the service;

(b) Prohibits a provider from advertising the provider's rates for a service.

(2) Division (B)(1)(b) of this section shall not be construed as prohibiting a provision in a contract between a provider and a third-party payer that prohibits a provider from disclosing or advertising contractually agreed upon reimbursement rates for providers.

(C)(1) This section shall apply to all new contracts between a third-party payer and a provider entered into on or after the effective date of this section.

(2) For existing contracts, this section shall apply on the earlier of either of the following:

(a) Three years after the effective date of this section;

(b) The expiration date of the contract or renewal of the contract.