State v. Ratliff, 2020 Ohio 3315

On Nov. 15, 2018 at ~12:15 a.m. Officer Matt Kellum followed Deborah Ratliff on Pleasant Avenue and observed conduct he believed suggested impairment.
Kellum testified he "paced" Ratliff using his cruiser speedometer and estimated her speed at 48–52 mph in a posted 35 mph zone.
Kellum also observed Ratliff weave within her lane, "bouncing" toward the right curb and nearly striking it several times; roadway was wet with sleet.
Ratliff was stopped, arrested, and registered a .167 BAC on a breath test.
Ratliff moved to suppress, arguing the stop relied on an "unaided visual" speed estimate barred by R.C. 4511.091(C)(1); the trial court denied the motion and the appellate court affirmed.

Issue	Plaintiff's Argument (Ratliff)	Defendant's Argument (State)	Held
Whether Kellum had reasonable suspicion to make an investigative stop	Stop was premised on an unaided visual speed estimate (statutorily prohibited), so no reasonable suspicion	Kellum paced using his cruiser speedometer (mechanical device) and observed erratic driving and bad-weather conditions — totality supports reasonable suspicion	Affirmed: reasonable suspicion existed; pacing + erratic driving in context justified stop

Terry v. Ohio, 392 U.S. 1 (established investigative/Terry-stop doctrine)
Ornelas v. United States, 517 U.S. 690 (review of reasonable suspicion/probable cause analyzed de novo)
United States v. Sokolow, 490 U.S. 1 (reasonable-suspicion standard is less demanding than probable cause)
State v. Mays, 119 Ohio St.3d 406 (Ohio 2008) (officer need not resolve potential legal defenses before effecting a stop)
State v. Batchili, 113 Ohio St.3d 403 (Ohio 2007) (reasonable-suspicion analysis requires totality of circumstances)
State v. Andrews, 57 Ohio St.3d 86 (Ohio 1991) (reasonable-suspicion viewed through eyes of reasonable officer on scene)
State v. Hairston, 156 Ohio St.3d 363 (Ohio 2019) (clarifies reasonable-suspicion standard and application)