A constitution is the fundamental law of a state or nation. It is a written document agreed to by the people and thus derives its authority from those it governs. A constitution establishes the nature and character of the state or national government. It organizes government into various branches, prescribes their powers, and specifies the extent to which these powers may be exercised.

The Ohio Constitution   is the fundamental law of Ohio and is subject only to the restrictions of the United States Constitution, acts of Congress, and international treaties to which the United States is a party. It may be changed only by voter approval of proposed amendments. 

From A Guidebook for Ohio Legislators.