As you probably know, there are differences of opinion as to whether the duty to disclose information imposed on prosecutors by ABA Model Rule 3.8 is broader than the duty imposed by the constitutional standards in Brady v. Maryland. The ABA Standing Committee on Professional Responsibility held that it does in Formal Opinion 09-454, but a few jurisdictions have held otherwise. I have written about this in the past here. (And for all my posts on prosecutors' duty to disclose evidence go here.)
Courts or Ethics Committees have also decided the duty under rules of professional conduct is broader in Utah, Texas, North Dakota, Massachusetts and the District of Columbia. Courts or Committees have decided otherwise in Ohio, Oklahoma, Colorado, Louisiana and Wisconsin.
Now comes news that the New York City bar's ethics committee has issued an opinion holding that a prosecutor's ethical obligation to disclose exculpatory evidence is broader than the constitutional minimums
imposed by Brady v. Maryland. See N.Y.C. Bar Ass'n Comm. on Prof'l Ethics, Op. 2016-3, 7/22/15.
Thanks to the ABA/BNA Lawyers' Manual on Professional Conduct for all the links.
UPDATE 10-29-16: Legal Ethics in Motion has a comment here.