Citing a government website ?
Please.
Ok, so I rephrase that. You are the only person I know who has smoked enough pot to fail a field sobriety road test designed for drunk drivers. Allegedly.
Soooooo....you do not want to hear anything that contradicts your view point so you make fun of it? Really?
Right now it is the only thing to meaure impairment. That road test does not determine the substance that has caused the impairment on that the driver is impaired. If the driver shows no impairment then there is not an issue.
The issue is not whether their is a substance in the drivers system. The issue is only whether or not the driver is impaired.