Medical Marijuana's been available for patients with certain diseases and ailments for one week in Illinois. McLean County Sheriff Jon Sandage says impairment has to be determined before charges would be filed against a driver with a marijuana prescription. Others would be charged with only trace amounts of the drug in their system. Sandage says it'll be a while before the department can gauge the effect of the new law.
Sheriff Sandage says if standard field sobriety tests show a driver legally using medical marijuana is impaired, further testing would require blood be drawn. The legal limit in the state is four nanograms THC per milliliter of blood.