Wisconsin residents likely know that criminal suspects are guaranteed due process by the Fifth and Fourteenth Amendments of the U.S. Constitution, and they may also know that prosecutors are required to hand over all exculpatory evidence to defense attorneys during the discovery process. Mistrials may be declared when defendants in criminal cases are denied access to evidence that could either help to exonerate them or implicate another, but prosecutors who commit what are known as Brady violations rarely face any sanctions.
They are known as Brady violations because the U.S. Supreme Court ruled in Brady v. Maryland that withholding exculpatory evidence from criminal defendants violated rights guaranteed by the U.S. Constitution. The 1963 case involved a written confession that had been with held. The Supreme Court ruling made clear that turning over exculpatory evidence was a legal and ethical obligation, but prosecutors often say that they either did not know about the relevant evidence concerned or did not believe it to be exculpatory.
Prosecutors with an abnormal amount of mistrials may be scrutinized closely and disciplined if they have a history of Brady violations, but some legal observers believe that a database of these infractions could help to protect the constitutional rights of criminal defendants. They argue that prosecutors would be more careful if they knew that their mistakes or ethical lapses could be tracked.
Experienced criminal defense attorneys will generally scrutinize any evidence handed over by prosecutors carefully, and they could also compare what they have received with the evidence provided in earlier cases to identify avenues of investigation that police may have neglected or exculpatory evidence that prosecutors could have with heldd. Defense attorneys may also check police reports and search warrants to ensure that the constitutional rights of their clients were not violated.