In Illinois, a person is guilty of DUI if he or she drives under the influence of any drug or combination of drugs to a degree that renders the person incapable of safely driving, OR if there is any amount of a drug, substance, or compound (excluding THC below 5ng/ml) in the person's breath, blood, or urine resulting from the unlawful use or consumption of cannabis. 625 Ill. Comp. Stat. Ann. § 5/11-501(a) (West 2010).
(1) Driving under the influence of any drug or intoxicating compound
It is unlawful for a person to drive or operate a motor vehicle in Illinois if the person is under the influence of any drug or intoxicating compound to a degree that renders the person incapable of safely driving. Id. §§ 5/11-501(a)(3)-(4).
The fact that the driver is or has been legally entitled to use a drug or intoxicating compound shall not constitute a defense. Id. §§ 5/11-501(b).
(2) Operating a motor vehicle while there is any amount of a drug in the person's body (per se law)
It is unlawful person to operate a motor vehicle while there is any amount of a drug in the person's breath, blood or urine. Id. §§ 5/11-501(a)(6).
NOTE: Actual impairment is not an element of this offense. Cannabis metabolites can be detected in a person's body up to one month after use, thus it is possible to be convicted of this offense weeks after a person last ingested cannabis.
The fact that the driver is or has been legally entitled to use a drug or intoxicating compound shall not constitute a defense. Id. § 5/11-501(b).
Illinois allows law enforcement officials to conduct roadblocks under the Federal Constitution.
People v. Allen, 873 N.E.2d 30 (2007) – Where Arresting officer claimed defendant had breath which smelled like burnt cannabis, but stated it was impossible to tell whether defendant had any amount of cannabis in his breath or blood, and only other evidence was the admission that driver had smoked cannabis the night before, evidence was not sufficient to convict. Statute does not criminalize having breath that smelled like burnt cannabis. State needed some evidence that defendant had at least some cannabis in his breath, urine, or blood.
People v. Workman, 312 Ill. App.3d 305 (2000) – Officer's opinion as to whether a person is under the influence of drugs is circumstantial evidence that may be considered sufficient provided officer's relevant skills, experience, or training.
People v. Bitterman, 492 N.E.2d 582 (1986) --Influence of a drug or drugs is essential element of charge of driving under the combined influence of alcohol and drugs.
People v. Briseno, 799 N.E.2d 359 (2003) -- Evidence is sufficient to support conviction for DUI of cannabis if police officer detected odor of cannabis on defendant's breath and in defendant's car, and defendant admitted smoking cannabis before operating his motor vehicle.
People v. Shelton, 708 N.E.2d 815 (1999) – In order for police officer's opinion testimony regarding drug impairment to be admissible, the officer must have more than "limited training" in detecting drug use.
Illinois has per se drugged driving law enacted for the presence of THC in blood above 5ng/ml. The law states: