Ohio Rev. Code § 307.34
When the board of county commissioners is unable to ascertain the boundary lines of the county with certainty, or having ascertained the boundary line, if the board or officers of the adjoining county disregard the true line, the board of the former may commence and prosecute a civil action in the court of common pleas of such adjoining county, against the board of that county, to ascertain and establish such boundaries.
The board of such adjoining county shall be made a party to the action and summoned as in other cases. If the court finds that the boundary line, to ascertain which such suit is commenced, is not sufficiently ascertained, or that the officers of such adjoining county disregard the true boundary line, the court shall appoint a surveyor, who is not a resident of either of such counties, to ascertain and survey such boundary line and make report of such line to the court. Unless, for good cause shown, the report is set aside, it shall be conclusive between such counties. If the survey is not set aside the court shall order a record of it to be made and a copy transferred to the county auditor of each of such counties, and order and decree that such line be established as the true boundary line between the counties. The court shall enforce the decree by injunction, attachment, or otherwise, against the officers of either of such counties.
R.C. §307.34