Ohio Rev. Code § 4123.73
Any employer who employs less than three employees regularly in the same business, or in or about the same establishment, who pays into the state insurance fund the premiums provided by this chapter, is not liable to respond in damages at common law or by statute, for injuries or death of any such employees, wherever occurring, during the period covered by such premiums, provided the injured employee has remained in his service with notice, as provided in section 4123.83 of the Revised Code, that his employer has paid such premiums into the state insurance fund. The continuation in the service of such employer with such notice shall be deemed a waiver by the employee of his right of action.
Any person who employs one or more individuals who are not employees as defined in section 4123.01 of the Revised Code, who pays into the state insurance fund the premiums provided by this chapter, is not liable to respond in damages at common law or by statute for injuries or death of any such individuals, wherever occurring, during the period covered by such premiums, provided the injured individual has remained in the service of such person with notice that his employer has paid such premiums into the state insurance fund. The continuation in the service of such employer with such notice, as provided in section 4123.83 of the Revised Code, shall be deemed a waiver by the individual of his right of action.
R.C. §4123.73