The Ohio Supreme Court (NYTimes 5/3/07) "overturned a law that required a prosecutor's consent to allow felons who had pleaded guilty to seek DNA tests that could prove their innocence". The Times reports that other states have similar legislation. We know that innocent persons are convicted of crimes, and there is probably an even larger number of those who plead guilty to crimes that they did not commit----many in fear of going to trial and receiving a much longer sentence than the plea bargain provides. (Which may explain the reduction in criminal trials reported by Adam Liptak NYTimes 4/30/07.) There is no way to calculate how many such cases exist because the same fear precludes subsequent challenges.
But what is difficult to understand is why a state legislature would enact such a statute even if only one innocent person entered a guilty plea. The proffered justification for the denial is that it interferes with the peace of mind of the victim "if a convict sought a hearing on DNA tests". It is difficult to envision how a DNA test would involve the victim, but even if it did, one would think that a victim would prefer to be inconvenienced rather than run the risk of having an innocent person remain in prison while the real criminal roamed free.
The Ohio Supreme Court wisely overturned the legislation on the ground that it violated the separation of powers and declared that the legislature"may not impede the judiciary in its province to determine guilt in a criminal matter". We should be searching for ways to ease the plight of innocent persons confined for crimes they did not commit, no matter how small the number may be, rather than impose barriers to their exoneration.