Ohio Rev. Code § 4123.04
This chapter applies to employers and their employees engaged in intrastate commerce and also in interstate and foreign commerce, for whom a rule of liability or method of compensation has been or may be established by congress, only to the extent that their mutual connection with intrastate work may be and is clearly separable and distinguishable from interstate or foreign commerce, and then only when such employer and any of his employees working only in this state, with the approval of the bureau of workers' compensation, and so far as not forbidden by any act of congress, voluntarily accept the provisions of this chapter by filing written acceptances, which, when filed with and approved by the bureau, subject the acceptors irrevocably to this chapter to all intents and purposes as if they had been originally included in its terms, during the periods for which the premiums provided in this chapter have been paid. Payment of premium shall be on the basis of the payroll of the employees who accept.
R.C. §4123.04