A bill defining how high is too high to be behind the wheel of a car has made its way through the state’s House Judiciary Committee according to the Denver Post.

The bill sets the legal limit for driving under the influence of marijuana at 5 nanograms of active THC per milliliter of blood. And that may be a problem. The Post reports opponents saying it is too low and may catch some pot users who haven’t used for some time but still have that level of it in their systems. There seems to be a consensus that a law needs to be passed to keeps roads safe, but the biggest hurdle will be setting that level, and then finding language to make the bill a working piece of legislation.