A trial court cannot admit the results of a polygraph test into evidence simply at an accused's request. State v. Jamison, 49 Ohio St.3d 182, 190, 552 N.E.2d 180 (1990). A trial court can only admit polygraph test evidence if the prosecution and defense together stipulate beforehand that the defendant will take the polygraph and that the results of which test will be admitted to the court. Id.; State v. Souel, 53 Ohio St.2d 123.
In the event of a stipulation, the results of the polygraph test stil can only be admitted to the trial court if the court determines it is acceptable for corroboration or impeachment purposes. There is at least one reported decision in Ohio that finds polygraph results to be reliable on their own. State v. Sharma, 143 Ohio Misc.2d 27, 875 N.E.2d 1002, 2007-Ohio-5404(C.P.) (polygraph test results sufficiently reliable to permit their admission at trial).
If the defendant wants polygraph results admissible in his trial then (a) he needs to get the results stipulated by the prosecution (b) he better pass the polygraph and (c) convince the judge to let a jury hear the results. It is still very rare for a jury in Ohio to ever hear about polygraph results of an accused.