Tests that detect marijuana's active ingredient, THC, don't always do so in a way that reflects whether a person is impaired, as traces of THC can remain in the system long after use and individual tolerance varies widely. But the group says it is reasonably certain to believe that marijuana has contributed to the causes of some crashes and increased the risk of driving for some motorists.
So this is a statement they just pulled out of their rear end. I don't want to go much farther with this because I am certainly not defending pot or driving stoned but I like to see real objective evidence in these types of articles.
So zero tolerance for booze and pot, IOW a BAC of zero and a zero for THC. Wouldn’t bother me a bit.