DENVER (AP) - Colorado lawmakers are trying for a fourth time to set driving limits for marijuana users.
A bill scheduled for House debate Tuesday would say drivers should be considered impaired if their blood contains more than 5 nanograms of THC per milliliter.
THC is the psychoactive ingredient in marijuana.
The legislature has tried and failed three times to pass a driving-high blood standard.
This year's version is slightly different. It would allow accused drivers to argue they were sober despite a blood test above the legal threshold.
Frequent pot users argue their blood limits exceed 5 nanograms even while sober. Driving-high bills have passed the House in previous years, but failed in the Senate.
Supporters say that marijuana legalization makes the driving-high bill more important.
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