State v. Cameron, 2011 MT 276

At about 1:00 a.m. on October 31, 2009, Deputy Sheriff observed Cameron's vehicle drift onto the centerline four times over five miles.
The vehicle never crossed into the oncoming lane, but touched the centerline for ~100 yards at one point, prompting a suspicion of impairment.
Deputy stopped the vehicle and a breath test showed Cameron had a BAC of 0.155.
Cameron was charged in Justice Court with driving under the influence (DUI) and DUI per se.
Cameron moved to suppress the stop as lacking particularized suspicion; the Justice Court denied the motion.
Cameron pled guilty to DUI while reserving the right to appeal the suppression denial; the District Court affirmed the denial.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether the stop was supported by particularized suspicion	Cameron argues there was no particularized suspicion to stop.	State contends the stop was valid under totality of circumstances per Weer.	District Court did not err; stop supported by particularized suspicion.

State v. Flynn, 2011 MT 48 (Mont.) (standard for suppression review; articulates totality of circumstances and that defendant's later explanations do not negate a valid stop)
City of Missoula v. Moore, 2011 MT 61 (Mont.) (defines particularized suspicion factors and totality of circumstances)
Brown v. State, 2009 MT 64 (Mont.) (articulates requirements for particularized suspicion)
State v. Rutherford, 2009 MT 154 (Mont.) (explains evaluation of information reliability in stop)
State v. Weer, 2010 MT 232 (Mont.) (time of day, stop location, and driving behavior as permissible totality factors)
State v. Brander, 2004 MT 150 (Mont.) (quotations on forming reasonable suspicion from objective facts)
Lafferty, 1998 MT 247 (Mont.) (criticized as flawed precedent for suspicion in this context)
Morris v. State, 2001 MT 13 (Mont.) (discounted as precedent for similar reasons to Lafferty)