No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a Grand Jury, except in cases arising in the land or naval forces, or in the Militia, when in actual service in time of War or public danger; nor shall any person be subject for the same offence to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property, without due process of law; nor shall private property be taken for public use, without just compensation.
The combination of otherwise acceptable rules of criminal trials may in some instances deny a defendant due process. Thus, based on the particular circumstance of a case, two rules that (1) denied a defendant the right to cross-examine his own witness in order to elicit evidence exculpatory to the defendant1 and (2) denied a defendant the right to introduce the testimony of witnesses about matters told them out of court on the ground the testimony would be hearsay, denied the defendant his constitutional right to present his own defense in a meaningful way.2 Similarly, a questionable procedure may be saved by its combination with another. Thus, it does not deny a defendant due process to subject him initially to trial before a non-lawyer police court judge when there is a later trial de novo available under the state’s court system.3
When a conviction is obtained by the presentation of testimony known to the prosecuting authorities to have been perjured, due process is violated. The clause
cannot be deemed to be satisfied by mere notice and hearing if a State has contrived a conviction through the pretense of a trial which in truth is but used as a means of depriving a defendant of liberty through a deliberate deception of court and jury by the presentation of testimony known to be perjured. Such a contrivance . . . is as inconsistent with the rudimentary demands of justice as is the obtaining of a like result by intimidation.4
The above-quoted language was dictum,5 but the principle it enunciated has required state officials to controvert allegations that knowingly false testimony had been used to convict6 and has upset convictions found to have been so procured.7 Extending the principle, the Court in Miller v. Pate8 overturned a conviction obtained after the prosecution had represented to the jury that a pair of men’s shorts found near the scene of a sex attack belonged to the defendant and that they were stained with blood; the defendant showed in a habeas corpus proceeding that no evidence connected him with the shorts and furthermore that the shorts were not in fact bloodstained, and that the prosecution had known these facts.
This line of reasoning has even resulted in the disclosure to the defense of information not relied upon by the prosecution during trial.9 In Brady v. Maryland,10 the Court held
that the suppression by the prosecution of evidence favorable to an accused upon request violates due process where the evidence is material either to guilt or to punishment, irrespective of the good faith or bad faith of the prosecution. In that case, the prosecution had suppressed an extrajudicial confession of defendant’s accomplice that he had actually committed the murder.11
The heart of the holding in Brady is the prosecution’s suppression of evidence, in the face of a defense production request, where the evidence is favorable to the accused and is material either to guilt or to punishment. Important, then, are (a) suppression by the prosecution after a request by the defense, (b) the evidence’s favorable character for the defense, and (c) the materiality of the evidence.12
In United States v. Agurs,13 the Court summarized and somewhat expanded the prosecutor’s obligation to disclose to the defense exculpatory evidence in his possession, even in the absence of a request, or upon a general request, by defendant. First, as noted, if the prosecutor knew or should have known that testimony given to the trial was perjured, the conviction must be set aside if there is any reasonable likelihood that the false testimony could have affected the judgment of the jury.14 Second, as established in Brady, if the defense specifically requested certain evidence and the prosecutor withheld it,15 the conviction must be set aside if the suppressed evidence might have affected the outcome of the trial.16 Third (the new law created in Agurs), if the defense did not make a request at all, or simply asked for
all Brady material or for
anything exculpatory, a duty resides in the prosecution to reveal to the defense obviously exculpatory evidence. Under this third prong, if the prosecutor did not reveal the relevant information, reversal of a conviction may be required, but only if the undisclosed evidence creates a reasonable doubt as to the defendant’s guilt.17
This tripartite formulation, however, suffered from two apparent defects. First, it added a new level of complexity to a Brady inquiry by requiring a reviewing court to establish the appropriate level of materiality by classifying the situation under which the exculpating information was withheld. Second, it was not clear, if the fairness of the trial was at issue, why the circumstances of the failure to disclose should affect the evaluation of the impact that such information would have had on the trial. Ultimately, the Court addressed these issues in United States v. Bagley18.
In Bagley, the Court established a uniform test for materiality, choosing the most stringent requirement that evidence is material if there is a reasonable probability that, had the evidence been disclosed to the defense, the outcome of the proceeding would have been different.19 This materiality standard, found in contexts outside of Brady inquiries,20 is applied not only to exculpatory material, but also to material that would be relevant to the impeachment of witnesses.21 Thus, where inconsistent earlier statements by a witness to an abduction were not disclosed, the Court weighed the specific effect that impeachment of the witness would have had on establishing the required elements of the crime and of the punishment, finally concluding that there was no reasonable probability that the jury would have reached a different result.22
The Supreme Court has also held that
Brady suppression occurs when the government fails to turn over even evidence that is 'known only to police investigators and not to the prosecutor.' . . . '[T]he individual prosecutor has a duty to learn of any favorable evidence known to others acting on the government's behalf in the case, including the police.'23