Do you think prosecutors have an ethical duty to turn over evidence that tends to show that the person they convicted is innocent? You would think so but don't try to find that in the ethics rules that govern lawyers who are public prosecutors. It's not there. Do you think the rules of conduct governing prosecutors should require them to turn over evidence of innocence after convicting a person who likely did not commit the crime?
At its Midyear Meeting this month the American Bar Association's House of Delegates voted in favor of a proposal to amend Rule 3.8 of the ABA Model Rules of Professional Conduct to identify prosecutors’ obligations when they know of new evidence establishing a reasonable likelihood that a convicted defendant did not commit the offense of which he was convicted.
This doesn't mean a whole lot, though, unless each state formally revises their rules on the subject and there is no assurance that will occur. The ABA Model Rules are precisely that--model rules--which are not binding on any lawyer practicing in this country. Each state in the U.S. has its own ethics rules that are binding on the lawyers practicing in that state.
Prosecutors have an ethical obligation to do more than just convict. They are to see that justice is done. Prosecutors do not have a client they are beholden but they have a constituency to whom they are responsible. That constituency is the voters that put the prosecutor in office. Surely the public that elected a district attorney does not want persons who are wrongfully convicted to stay in prison. What if was you or a family member incarcerated in prison and the person holding the key to freedom is the prosecutor?
Unfortunately, most prosecutors do not recognize or accept their responsiblity to reveal evidence of innocence post-conviction and will likely oppose measures like the amendment recently adopted by the ABA.