I do know that a couple of European countries have established levels per se for the active ingredient of marijuana. But I'm not aware of any more recent research that establishes what basis they did that on, beyond what we had before.
I believe Corporal Graham is aware of research about how ineffective have been the attempts to detect drugs at the side of the road. Europe has been working on that, and we've been hoping they would come up with a roadside test that would help us on that.