A case that recently came before the Michigan Supreme Court, People v. Chenault, raised the question of whether defense counsel has to meet a due diligence requirement to obtain exculpatory or impeaching evidence for a Brady violation to occur. Since Brady was decided four decades ago, numerous courts (including the U.S. Court of Appeals for the 5th and 11th Circuits) have adopted a due diligence rule in their analysis of Brady claims. The three-prong test of a Brady violation, as outlined in Brady, was summarized again in Strickler (1999) as:
The evidence at issue must be favorable to the accused, either because it is exculpatory, or because it is impeaching; that evidence must have been suppressed by the State, either willfully or inadvertently; and prejudice must have ensued.
To add a due diligence prong to this test, courts are basically asking whether a defendant knew or could have known about suppressed evidence through their own initiative. If the answer is yes, a court will likely not find in a defendant’s favor.
In “Prosecutors Hide, Defendants Seek,” (60 UCLA L. REV. 138 (2012)), Kate Weisburd charts the development of due diligence rules as they apply to Brady and its progeny. The author finds that how courts define “due diligence” varies widely from state to state, and that though justifications for this rule are straightforward and have intuitive appeal, they are contrary to the Due Process Clause of the Constitution, as interpreted in Brady.
Ultimately, Weisburd finds that there is no strong legal footing for a due diligence rule:
[T]he defendant due diligence rule developed in a somewhat haphazard way: Some lower courts took one phrase out of context, and other lower courts borrowed language from outdated cause and prejudice analysis. As a result, courts now frequently apply a rule that has no legitimate doctrinal support.
Indeed, it was the 11th Circuit that the Michigan Court of Appeals relied upon to adopt its own due diligence rule in Lester (1998), which it in turn used to deny Chenault his Brady violation. The Michigan Supreme Court disagreed with the Court of Appeals this week, overruling Lester and denying that there is a due diligence requirement.
The Court agreed with Weisburd’s argument, outlining the reliance of various courts on other courts’ rulings in favor of a due diligence requirement and concluding, “None of these cases, however, provides a sufficient explanation for adding a diligence requirement to the Supreme Court’s three-factor Brady test and are consequently of little value to us.” (p. 7-8)
The Court continued,
We disagree with the prosecution’s suggestion that the diligence requirement is consistent with or implied by United States Supreme Court precedent. Nor do we conclude that a diligence requirement is consistent with the Brady doctrine generally. We believe that the concerns that a diligence requirement might address are already confronted in the context of Brady’s suppression requirement as well as in the Sixth Amendment’s guarantee of the effective assistance of counsel. For these reasons, we reject the addition of a diligence requirement to the Brady test and we overrule Lester. (p. 8)
The Court nevertheless found that the exculpatory evidence withheld by the state in Chenault’s case was not material to his conviction, and upheld the Court of Appeals’ ruling on that count.