People v. Kavanaugh, 72 N.E.3d 394

On May 13, 2015, Adalie M. Kavanaugh was involved in a lane-change incident in which another vehicle went into a ditch; she admitted cutting off that vehicle but her car did not make contact.
Trooper Matt Windisch stopped Kavanaugh, smelled a strong odor of burnt cannabis from her vehicle, and located cannabis, a grinder, and a pipe in the car.
Kavanaugh told the trooper she had smoked cannabis roughly one week earlier; the trooper did not smell cannabis on her breath or observe impaired gait but believed the odor in the car was freshly burnt.
Windisch administered and scored field sobriety tests (walk-and-turn, one-leg stand) and performed an ocular convergence test; he concluded Kavanaugh failed the sobriety tests and displayed a strong lack of convergence in her left eye.
At the statutory-summary-suspension rescission hearing the trial court rejected the convergence test (no scientific foundation), found the field tests did not show failure when viewed on video (performed on an interstate shoulder with heavy traffic), and emphasized no odor on Kavanaugh’s person. The court granted rescission.
The State appealed; the appellate court reversed, holding that the lane violation, strong odor in the vehicle, and presence of cannabis and paraphernalia provided reasonable grounds to believe Kavanaugh was driving under the influence of cannabis.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether the arresting officer had reasonable grounds (probable cause) to believe Kavanaugh was driving under the influence of cannabis	The lane violation plus strong odor of freshly burnt cannabis in the vehicle, and cannabis/paraphernalia found, supported reasonable grounds to arrest	The trooper lacked sufficient evidence of impairment: no odor on Kavanaugh’s person, field tests on video did not show clear failure, and the convergence test lacked scientific foundation	Reversed trial court: under the probable-cause standard the combination of erratic driving, strong odor in the vehicle, and discovery of cannabis/paraphernalia provided reasonable grounds to believe DUI by cannabis had occurred; convergence test properly excluded for lack of foundation

First Capitol Mortgage Corp. v. Talandis Constr. Corp., 63 Ill.2d 128 (1976) (failure to file appellee brief permits decision if record is simple or demonstrates prima facie reversible error)
People v. Wear, 229 Ill.2d 545 (2008) (probable cause standard for reasonable grounds under statutory-summary-suspension analysis)
People v. Brodeur, 189 Ill. App.3d 936 (1989) (vehicle accident/erratic driving can support probable cause for DUI)
People v. Luedemann, 222 Ill.2d 530 (2006) (deference to trial court factual findings; de novo review of legal ruling)
People v. Garvin, 219 Ill.2d 104 (2006) (probable cause requires probability of criminal activity, not proof beyond a reasonable doubt)
People v. Lee, 214 Ill.2d 476 (2005) (same standard for probable cause discussion)
People v. Rozela, 345 Ill. App.3d 217 (2003) (need adequate foundation to admit novel/specialized test results)
Frye v. United States, 293 F. 1013 (D.C. Cir. 1923) (standard for admissibility of novel scientific evidence)