Montana DUI Guide

Discovery in a Montana DUI Case: What You Are Entitled to See

A DUI case is built on reports, recordings, and test records. Discovery is how the defense gets them, and the statute puts the first move on you.

Written by

Misty Gaubatz, Partner, A&M Law

Licensed Montana attorney and co-founder of A&M Law. Over two decades in the practice of law focusing on family law, criminal defense, and DUI defense, with federal and state court experience and a Certificate in Mediation.

Montana Bar #122346+ years as an attorney, with over two decades working in the lawReviewed by Ashley HurlbertLast reviewed: October 9, 2026

Key Takeaways: Discovery in a DUI Case

Montana's disclosure statute works "upon request": the prosecutor must make the listed material available once the defense asks (MCA § 46-15-322(1)).
The duty covers witness statements, your own statements, expert reports and test results, physical evidence, and anything favorable to you.
It reaches material held by anyone who took part in the investigation, not only what is in the prosecutor's file (MCA § 46-15-322(4)).
A separate DUI statute entitles you to full information about any test given at an officer's direction (MCA § 61-8-1019(3)).
Discovery runs both ways. The defense has its own disclosure duties, with a 30-day clock from arraignment (MCA § 46-15-323).
Both sides have a continuing duty to disclose, and a court can sanction a party that does not comply (MCA §§ 46-15-327, 46-15-329).

Discovery is the exchange of evidence before trial. In a Montana DUI case, once the defense asks, the prosecutor must make available the witness statements, your own statements, test results and expert reports, physical evidence, and anything that helps your side (MCA § 46-15-322(1)). Until that material is in hand, no one can tell you honestly how strong the case is. This page is part of our Montana DUI Guide and expands the pretrial stage of the DUI court process.

What the Prosecution Must Disclose

The core statute is MCA § 46-15-322. "Upon request," the prosecutor must make the following available "for examination and reproduction" if it is within the prosecutor's possession or control:

Category	What it covers	MCA
Witnesses	Names, addresses, and statements of everyone the prosecutor may call in the case in chief.	§ 46-15-322(1)(a)
Your own statements	All written or oral statements of the defendant.	§ 46-15-322(1)(b)
Expert reports and test results	Reports of experts who examined you or the evidence, with the results of scientific tests.	§ 46-15-322(1)(c)
Documents, photos, objects	Anything the prosecutor may use at trial, or that was obtained from you.	§ 46-15-322(1)(d)
Favorable information	Anything that tends to mitigate or negate guilt, or would tend to reduce a sentence.	§ 46-15-322(1)(e)

Two features of the statute matter in practice. First, it is triggered by a request, so the request should go out at the start of the case. Second, the obligation is not limited to the prosecutor's own file. It "extends to material and information in the possession or control of members of the prosecutor's staff and of any other persons who have participated in the investigation or evaluation of the case" (MCA § 46-15-322(4)). In a DUI case that includes the arresting agency.

What That Looks Like in a DUI File

The statute speaks in categories. In a DUI case, the defense request usually names specific items within them:

The officer's reports, including the narrative, the field sobriety test notes, and the implied consent advisory form.
Video and audio: dash camera, body camera, and any recording from the jail or the breath test room. See body camera and dash video.
Dispatch records and any caller report that led to the stop.
Breath test records: the printed result, the operator's certification, and the instrument's field certification records under ARM 23.4.213.
Blood test records: the draw paperwork, chain of custody, and the laboratory report. See crime lab and toxicology reports.
Your statements, whether written down, recorded, or simply remembered by the officer.
Prior conviction records the State intends to rely on to charge a second or later offense.

Not every case has every item. A stop with no camera has no video to disclose. Part of the work is finding out what exists, what was never created, and what was created but not kept.

The DUI-Specific Right to Test Information

Apart from the general discovery statute, the DUI code has its own rule: "Upon the request of the person tested, full information concerning any test given at the direction of the peace officer must be made available to the person or the person's attorney" (MCA § 61-8-1019(3)).

That matters because a test report is only admissible if certain conditions are met. A breath test must have been performed by a person certified by the Forensic Science Division, and a blood sample must have been analyzed in a laboratory operated or certified by the department (or exempt under its rules) and drawn by a person qualified to do so (MCA § 61-8-1018(1)(b)). The records behind the result are how the defense checks those conditions. Our pages on challenging the breath test and challenging the blood test explain what those records can show.

When the Defense Needs More

Some useful material falls outside the listed categories, or is held by someone other than the prosecution team. The statute provides a route. On a motion showing that the defendant has "substantial need" for additional material and cannot obtain the substantial equivalent by other means without undue hardship, the court may order "any person" to make it available (MCA § 46-15-322(5)). The person affected can ask the court to modify the order if compliance would be unreasonable or oppressive.

There are limits. Disclosure is not required for an attorney's superseded notes or work product, except that exculpatory information in the prosecution's work product must still be disclosed (MCA § 46-15-324(1), (2)). A court may also defer or regulate a disclosure, or allow part of a document to be withheld, on a showing of good cause (MCA § 46-15-328). And the prosecutor cannot be required to prepare summaries of what witnesses will say.

What the Defense Must Disclose

Discovery is reciprocal. Within 30 days after arraignment, or at a later time the court permits for good cause, the defense must:

Give written notice of an intent to rely on certain defenses, such as alibi, compulsion, or mistaken identity (MCA § 46-15-323(2)).
Make available the names, addresses, and statements of the witnesses it may call, other than the defendant (MCA § 46-15-323(6)(a)).
Disclose the experts it may call, with their test results and reports (MCA § 46-15-323(6)(b)).
Make available the documents, photographs, and objects it may use at trial (MCA § 46-15-323(6)(c)).

If you hire a toxicologist or have an independent blood test you plan to use, those results are covered. The 30-day period is easy to overlook when you are focused on what the State owes you.

A Continuing Duty, and Sanctions

Disclosure is not a one-time event. If a party discovers additional material that would have been subject to disclosure, it must "promptly notify all other parties" and disclose it (MCA § 46-15-327). A late lab report or a second officer's video falls under this rule.

When a party does not comply, the court "may impose any sanction that it finds just under the circumstances." The statute lists ordering disclosure, granting a continuance, holding someone in contempt for an intentional violation, precluding a witness or evidence, and declaring a mistrial when necessary (MCA § 46-15-329). The choice is the judge's. A defense request for more time because of late discovery can also affect the six-month trial deadline, so the two should be considered together.

Timing: Why the Request Goes Out First

Pretrial issues generally must be raised at or before the omnibus hearing (MCA § 46-13-101(1)). A motion to suppress cannot be written responsibly without the reports and the video. So the order of work is fixed: request discovery, review it, then decide on motions. A plea offer that arrives before the evidence does is an offer you cannot yet evaluate.

This page explains Montana procedure in general as of the 2025 Montana Code Annotated. Local practice varies by court. It is not legal advice about your specific case.

Montana DUI Guide DUI Defense Motions to Suppress Speedy Trial Deadlines DUI Plea Agreements The DUI Jury Trial

FAQ

Discovery in a Montana DUI Case: What You Are Entitled to See FAQ

Can I get the police report and video in my own DUI case?

Yes. On request, the prosecutor must make available the reports, statements, test results, and recordings covered by MCA § 46-15-322 for examination and reproduction. If you have an attorney, the request goes through that office. If you represent yourself, you make the request to the prosecutor in writing.

How long does discovery take in a DUI case?

The statute does not set a number of days for the prosecutor's initial disclosure. Reports, video, and laboratory results often arrive at different times, and a blood analysis can take longer than the rest. If material is slow, the remedy is a motion asking the court to order disclosure.

Does the prosecutor have to give me evidence that helps my case?

Yes. The statute requires disclosure of all material or information that tends to mitigate or negate guilt or that would tend to reduce the potential sentence (MCA § 46-15-322(1)(e)). Even a prosecutor's work product must be disclosed to the extent it contains exculpatory information (MCA § 46-15-324(2)).

What if the prosecution turns over evidence late?

The court may impose any sanction it finds just, including ordering disclosure, granting a continuance, or precluding the party from calling a witness or offering the evidence (MCA § 46-15-329). Which one a judge chooses depends on the circumstances, including why the material was late and whether the defense was harmed.

Do I have to give the prosecutor anything?

Yes, within limits. Within 30 days after arraignment, or later if the court allows for good cause, the defense must make available the names and statements of its witnesses other than the defendant, expert results, and documents it may use at trial (MCA § 46-15-323(6)). The witness duty covers people other than the defendant.

Want Someone to Read the Evidence With You?

We request the full file and go through the reports, the video, and the test records before advising you. Call 406-830-3060 for a confidential consultation.

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