State v. Robertson, 440 P.3d 17

Deputy Esteves stopped Robertson after observing unsafe driving and detected a strong odor of marijuana; Robertson and a passenger voluntarily produced marijuana and a glass pipe.
Esteves observed signs of impairment, performed field sobriety tests, and obtained a preliminary breath test of 0.114; Robertson was arrested for DUI and later blood tested at 0.112.
Esteves obtained a search warrant for Robertson’s truck; the search recovered 111.2 grams of marijuana and paraphernalia.
Robertson was charged (later amended to misdemeanor possession) with possession of dangerous drugs, possession of drug paraphernalia, and DUI; he moved to suppress the vehicle search, to exclude the arresting officer’s testimony, and to dismiss the DUI for failure to preserve jail video.
The District Court denied the motions; following a jury trial Robertson was convicted of three misdemeanors and sentenced; he appealed.

Issue	Robertson's Argument	State's Argument	Held
Whether arresting officer should be barred from testifying for lack of required peace-officer certification	Esteves’s wellness exam was allegedly insufficient and possibly performed by his personal physician, so he lacked certification and should be barred	Officer need not be certified to testify about his personal observations; no authority bars testimony for uncertified officers	Court affirmed: officer may testify based on personal knowledge; Robertson offered no authority showing disqualification
Whether search warrant lacked probable cause	Warrant application allegedly insufficient to show fair probability of finding contraband	Officer observed odor of marijuana and recovered marijuana and pipe; warrant described truck and expected evidence	Court affirmed: totality of circumstances supported probable cause and warrant particularity
Whether State’s failure to preserve detention-center video warrants dismissal for Brady violation	Overwritten video would have shown sobriety and was favorable/exculpatory	Video was overwritten negligently but Robertson’s claim is speculative and not shown to be material to outcome	Court affirmed: no prima facie Brady violation; lost video was not shown to be exculpatory or outcome-determinative

Illinois v. Gates, 462 U.S. 213 (totality-of-the-circumstances test for probable cause)
State v. Barnaby, 142 P.3d 809 (Mont. 2006) (probable-cause and warrant standards)
State v. Kasparek, 375 P.3d 372 (Mont. 2016) (deference to issuing judge; fair-probability standard)
State v. Ilk, 422 P.3d 1219 (Mont. 2018) (Brady analysis; burden on defendant)
State v. Weisbarth, 378 P.3d 1195 (Mont. 2016) (materiality standard for suppressed evidence)
McGarvey v. State, 329 P.3d 576 (Mont. 2014) (negligent suppression requires evidence to be material, vital, and exculpatory)