A DUI Prosecutor Must Help Prove That You Are Not Guilty

by baronedefensefirm on September 22, 2009

In a Michigan drunk driving case the prosecutor is legally and ethically required to provide the evidence that shows that you are not guilty. 

Unfortunately, not all defense lawyers know how to make sure the prosecutor provides this favorable evidence, and not all prosecutors follow the law or ethics.

Both the prosecutor and the defense attorney have constitutional roles in a DUI prosecution.  These constitutional roles are intended to ensure fairness and also ensure that an innocent person is not convicted of drunk driving.

The DUI Defense Attorney’s Constitutional Role:

A drunk driving defense attorney’s constitutional role is to ensure due process.  While not easy to define, “due process” essentially means fairness.  Among many others, due process rights include the right to confront the witnesses and evidence against you, the right to have an attorney represent you, the right to remain silent and the right to a trial by jury.

The rule of a defense attorney cannot be fulfilled without comprehensive pre-trial discovery. In other words, a drunk driving prosecution cannot be fair unless you have the ability to see all the evidence, both good and bad, that the prosecutor has in your case.

Consequently, comprehensive discovery is fundamental to assuring that the constitutional guarantees of a fair trial and to due process of law are not violated.  

In order to have complete discovery there is much information that should be sought in a drunk driving case.  The majority of this information relates to the elements that the state must prove, the burden of proof, and any defenses available to the defendant.

The right to complete discovery means the defen­dant is also entitled to any information concerning the qualifications of the arresting officer, the breath test operator, and any other information concerning field sobriety tests, horizontal gaze nystagmus tests or chemical tests administered as part of the drunk driving investigation.

It is only when the defendant has this information available for review and analysis that he will be able to prepare an adequate defense and be specifically able to attack the chemical test administered.

On the other hand, without the right to the discovery of such information the drunk driving statutes, and in particular the per se statutes, would likely be unconstitu­tional[i].

However, the existence and extent of a prosecutor’s obligation to provide discovery has evolved over the past century.  This evolution has taken place most rapidly over the past fifty-plus years. 

Prior to that time there was a legitimate question as to whether or not the defendant had any right to discovery whatsoever. This position was set forth in 1958 by the United States Supreme Court who held that the states were not constitutionally required to provide discovery to a defendant in a criminal case[ii]. 

Just five years later the same court held that prosecutors did have a constitutional obligation to provide “material” discovery[iii].  In this case the United States Supreme Court further provided for a remedy of suppression where such evidence was not provided to the defense.  Such undisclosed information must however be material either to guilt or to punishment, irrespective of the good faith or bad faith of the prosecution[iv].”

Previously a prosecutor’s obligation to provide material discovery well-established at the federal level but had not yet been extended under the Due Process Clause to state court proceedings[v].  Most states now recognize that this obligation to provide material evidence also applies at the state level.

Definition of Material Evidence:

“Material” information is defined as that which is likely to lead to an acquittal[vi].  This is obviously a very subjective determination.  In an effort to clarify what this means, the United States Supreme Court has said:

“[T]he materiality inquiry is not just a matter of determining whether, after discounting the inculpatory evidence in light of the undisclosed evidence, the remaining evidence is sufficient to support the jury’s conclusions. Rather, the question is whether ‘the favorable evidence could reasonably be taken to put the whole case in such a different light as to undermine confidence in the verdict[vii].

As the duty of disclosure has progressed the nature of the prosecutor’s constitutional duty to disclose has shifted from (a) an evidentiary test of materiality that can be applied rather easily to any item of evidence (would this evidence have some tendency to undermine proof of guilt?) to (b) a result-affecting test that obliges a prosecutor to make a prediction as to whether a reasonable probability will exist that the outcome would have been different if disclosure had been made[viii].

The DUI Prosecutor’s Constitutional Role:

A prosecutor’s constitutional role is obviously different from a defense attorney’s constitutional role.  A prosecutor’s constitutional role is simply to ensure justice.  A prosecutor’s role in a drunk driving case is not to obtain a conviction.  This is because even in a drunk driving case there are times when a conviction is not justice.

The reason a prosecutor’s role is not to obtain a conviction is because prosecutors have special obligations as representatives “not of an ordinary party to a controversy, but of a sovereignty whose obligation to govern impartially is as compelling as its obligation to govern at all; and whose interest, therefore, in a criminal prosecution is not that it shall win a case, but that justice shall be done[ix].”

A DUI Prosecutor’s Ethical Obligations To Provide Favorable Evidence:

In addition to the constitutional duty of a prosecutor to disclose, there is also the ethical obligation of a prosecutor to provide favorable discovery. 

In Formal Opinion 09-454 the American Bar Association’s Standing Committee on Ethics and Professional Responsibility sets forth what they believe to be the prosecutor’s ethical duty to disclose evidence and information favorable to the defense. 

That opinion interprets Model Rule of Professional conduct 3.8(d) which provides as follows:

Rule 3.8(d) requires a prosecutor who knows of evidence and information favorable to the defense to disclose it as soon as reasonably practicable so that the defense can make meaningful use of it in making such decisions as whether to plead guilty and how to conduct its investigation.

Prosecutors are not further obligated to conduct searches or investigations for favorable evidence and information of which they are unaware.

In connection with sentencing proceedings, prosecutors must disclose known evidence and information that might lead to a more lenient sentence unless the evidence or information is privileged.

Supervisory personnel in a prosecutor’s office must take reasonable steps under Rule 5.1 to ensure that all lawyers in the office comply with their disclosure obligation.

The Difference in the DUI Prosecutor’s Constitutional and Ethical Obligations:

Relative to DUI prosecutors the big difference in the model rule as compared with the constitutional obligation is that the model rule requires disclosure of information “favorable” to the defense in a drunk driving case rather than the more narrow requirement to disclose information that is “material.”  

In this context the word “material” has been meaning essentially exculpatory whereas “favorable” more broadly includes evidence that may exonerate.

Thus it may be said that Rule 3.8(d) requires the prosecutor only to determine if the evidence or information is “favorable.”  It does not require the prosecutor to consider the anticipated impact of the evidence or information on a trial’s outcome.

According to the opinion the drafters of Rule 3.8(d) made no attempt to codify the constitutional obligation but instead sought to establish an independent one. The ethical obligation suggested by the ABA is clearly more demanding than the constitutional obligation and the prosecutors’ ethical duty of disclosure extends beyond the constitutional obligation.

The opinion further states that a prosecutor’s ethical duty of disclosure extends beyond what is traditionally thought of as “evidence” to what is more broadly referred to as “information.” 

While a prosecutor’s obligation clearly extends beyond just the police reports, witness statements, maintenance records and transcripts, the word “information” is not defined.

Nevertheless, the opinion makes it clear that in determining whether any evidence or information is favorable the prosecutor must consider defenses that the defendant has expressed an intention to raise as well as any other legally cognizable defenses.

Additionally, there is nothing in the rule that suggests that a prosecutor may fail to disclose information believed to have only a minimal tendency to negate the defendant’s guilt.  The rule is broad enough to include even “highly unreliable” evidence provided such evidence is “favorable.”

There is however a knowledge requirement and this means either actual knowledge or knowledge which may be inferred from the circumstances. On the other hand there is no affirmative duty for the prosecutor to independently investigate the case.

A DUI Defense Attorney May Not Agree to Waive Discovery:

Interestingly, a prosecutor may not accept a defendant’s consent to noncompliance with the rule. For example, the prosecutor and the defendant in a drunk driving case may not agree that in exchange for non-disclosure there will be a more favorable outcome for the defendant.  In fact, a prosecutor may not even ask for such an agreement.

How This Information Helps Those Charged with Drunk Driving:

Although ABA Opinions are only advisory and without force of law states can incorporate this new opinion into both state law or state rules of ethics.  The ABA opinion indicates:  

[W]e are aware of only two jurisdictions where courts have determined that prosecutors are not subject to discipline under Rule 3.8(d) for withholding favorable evidence that is not material under the Brady line of cases. 

At the Barone Defense Firm we endeavor to insist that prosecutors always provide all material and favorable information so that we can review it prior to either a plea or trial.  It is only after such full and fair discovery that your rights can be adequately protected.

If you have been charged with drunk driving (OWI) in Michigan, Contact the Barone Defense Firm today for your FREE case review.  During this review we can discuss how we can use these cases and laws about pretrial discovery to your benefit.


[i] See e.g., California v. Trombetta, 467 U.S. 479 (1984); Fuenning v. Superior Court, 139 Ariz. 590, 680 P.2d 121 (Ariz. 1983).


[ii] See Cicenia v. Lagay, 357 U.S. 504 (1958).

[iii] See Brady v. Maryland, 373 U.S. 83 (1963).  


[iv] See also Kyles v. Whitley, 514 U.S. 419, 432 (1995) (“The prosecution’s affirmative duty to disclose evidence favorable to a defendant can trace its origins to early 20th-century strictures against misrepresentation and is of course most prominently associated with this Court’s decision in Brady v. Maryland.”) 


[v] See, e.g., Jencks v. United States, 353 U.S. 657, 668, n. 13 (1957).


[vi] See, e.g., Strickler v. Greene, 527 U.S. 263, 281-82 (1999); Kyles, 514 U.S. at 432-35, United Statesv. Bagley, 473 U.S. 667, 674-75 (1985).


[vii]Strickler, 527 U.S. at 290 (citations omitted).  


[viii] See United States v. Coppa, 267 F.3d 132, 142 (2d Cir. 2001).


[ix] See Berger v. United States, 295 U.S. 78, 88 (1935) where the court discusses judicial decisions regarding the prosecutor’s obligation to seek justice that date back more than 150 years.


This post was written by...

– who has written 204 posts on Michigan Drunk Driving Lawyers.

Patrick T. Barone is the author on two books on DUI defense including the well respected two volume treatise Defending Drinking Drivers (James Publishing), and The DUI Book – A Citizen’s Guide to Understanding DUI Litigation in America. He is also the author of a monthly DUI defense column for the Criminal Defense Newsletter, published by Michigan’s State Appellate Defender’s Office. Mr. Barone is an adjunct professor at the Thomas M. Cooley Law School where he teaches Drunk Driving Law and Practice. He is also on the faculty of the Criminal Defense Attorney’s of Michigan’s Trial Lawyer’s College where he provides trial skills training to Michigan’s criminal defense practitioners. Mr. Barone lectures nationally on various DUI defense topics, and he has appeared in newspapers, on television and on radio as a drunk driving defense expert. Mr. Barone has been certified as an instructor and practitioner of the Standardized Field Sobriety Tests and has also attended a 24-hour certification course at National Patent Analytical Corporation (the manufacturer of the DataMaster) and has thereby been deemed competent by the manufacturer to operate, perform essential diagnostic verifications and calibration checks on the DataMaster. Mr. Barone is a Sustaining Member of College for DUI Defense. Mr. Barone is the principal and founding member of The Barone Defense Firm, whose practice is limited exclusively to defending drinking drivers. The Firm is headquartered in Birmingham, Michigan.

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