For those not familiar with the Supreme Court case Brady v. Maryland, it holds that a prosecutor has an affirmative duty to disclose material evidence favorable to the defense. It’s a simple enough directive, but the details of what comprises exculpatory evidence and whether the prosecutor has control of the evidence gets complicated.
And that’s just from the pretrial perspective.
If you’ve been convicted and are trying to argue that the prosecutor failed to disclose exculpatory evidence after the fact, you will run into surprising limitations on what you can argue.