State v. S. Walston, 469 P.3d 716

In March 2016 a confidential informant (CI) working with the Missouri River Drug Task Force conducted a recorded, supervised controlled buy from Shawn Walston; the CI was searched before and after the buy and handed officers a bag that field‑tested positive for methamphetamine.
The CI wore a body wire; officers could hear parts of the conversation but could not see inside Walston’s trailer; much of the audio was unintelligible at trial.
The State charged Walston with distribution and possession of methamphetamine; the State refused to disclose the CI’s identity in discovery and the district court denied Walston’s motion to compel disclosure or dismiss.
At the second trial five officers testified about the operation; the CI did not testify and Detective Barnes said the CI had moved away and no longer worked for the Task Force; the jury convicted Walston on both counts.
On appeal the narrow issue was whether the district court erred in denying disclosure of the CI’s identity; the Supreme Court reversed, holding the CI had played a continuous, active, primary role and the State failed to prove substantial risk from disclosure.
Result: conviction vacated and case remanded; if the State again refuses to disclose the CI identity, the court must dismiss the charges related to that testimony.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether the district court erred in denying Walston’s motion to disclose the CI’s identity	State: CI not testifying; burden on Walston to show more than speculation of relevance and to overcome informant privilege and safety concerns	Walston: CI was an active participant and the only other eyewitness; identity is necessary for confrontation, cross‑examination, and to prepare defense	Reversed: CI played a continuous, active, primary role; State failed to show substantial risk from disclosure; CI identity must be disclosed or charges dismissed

Roviaro v. United States, 353 U.S. 53 (U.S. 1957) (articulates informant‑identity privilege and balancing test; disclose when identity is relevant, helpful, or essential)
State v. Chapman, 209 Mont. 57 (Mont. 1984) (Montana applies Roviaro; disclose where informant played a continuous, active, primary role)
State v. McLeod, 227 Mont. 482 (Mont. 1987) (mere conjecture about relevancy insufficient to compel disclosure)
United States v. Kerris, 748 F.2d 610 (11th Cir. 1984) (two key factors: extent of CI participation and directness of CI testimony to asserted defense)
State v. Babella, 237 Mont. 311 (Mont. 1989) (disclosure denied where defendant failed to show informant’s testimony would significantly aid defense and where disclosure posed demonstrable safety/operational risks)