For the ordinary Illinois THC concentration rule, what pair of thresholds is specified by law?

Correct answer: 5 nanograms per milliliter of whole blood or 10 of another bodily substance.

Why

The thresholds are 5 nanograms or more of delta-9-THC per milliliter of whole blood, or 10 nanograms or more per milliliter of another bodily substance, within 2 hours of driving or actual physical control. The concentration-only rule has a proviso for lawful use by a qualifying medical-cannabis patient possessing a valid registry card unless impaired. No driver may drive impaired, even if use was lawful or a measured concentration was lower.

Verified against Illinois Rules of the Road, July2026 · THC concentration limits · p. 51