To fully understand what constitutes a Brady violation, it is essential to explore the case of Brady v. Maryland itself. John Leo Brady and a companion, Charles Boblit, were convicted of first-degree murder in the state of Maryland. During the trial, Brady admitted his involvement in the crime but argued that Boblit was the one who actually committed the murder. Brady's defense requested access to Boblit's statements, but the prosecution withheld one crucial statement in which Boblit confessed to the murder.
Although Brady was convicted and sentenced to death, his legal team discovered the withheld confession during post-trial proceedings. Brady appealed, arguing that the suppression of this exculpatory evidence violated his constitutional rights. The U.S. Supreme Court ultimately agreed with Brady, ruling that the suppression of evidence favorable to the defendant by the prosecution violates the Due Process Clause of the Fourteenth Amendment. This ruling laid the groundwork for what is now known as a "Brady violation."