And in a related story, Colorado is moving toward setting the THC level that would define DUI for potheads. The allowable level might be quite low. (Of course the legal level the feds would recommend would be 0.0 nanograms.)
"A Colorado House committee advanced a bill to set marijuana blood limits for drivers Monday.
House Bill 1114, also known in previous years as the marijuana DUI bill, would say that drivers are legally impaired if their blood contains more than 5 nanograms of THC per milliliter. THC is the psychoactive ingredient in marijuana."
Warning: Dated material. It's happening, but the above story might not reflect the latest developments.