The nation's most liberal driving-while-high standards have been rejected by the Colorado Senate, even as lawmakers sign off on other regulations about medical marijuana.
The Senate narrowly rejected a pot DUI proposal Monday that would have set a driving impairment standard of 5 nanograms of THC per milliliter of blood. THC is the psychoactive ingredient in marijuana.
That would have been the country's most liberal limit and was approved by the House. But medical marijuana advocates and some Republicans opposed it, saying there isn't enough research on the matter to set a limit.
Senators gave preliminary approval to a separate bill banning synthetic marijuana known as "Spice" or "K2." Lawmakers also approved new regulations for selling medical marijuana.