The race is on to build a viable pot breathalyser, as cannabis is becoming increasingly legally available around the world.
Reuters reports that a Canadian company called Cannabix (which sounds more like a whole-grain breakfast cereal for Snoop Dogg) is working on a device that roadside police will be able to carry to check that drivers aren't stoned at the wheel.
Apparently the challenge is in creating a device that will detect THC, the psychoactive substance found in cannabis.
The first devices won't be too sophisticated - merely offering a binary yes or no as to whether THC has been detected (rather than offering a more nuanced calculation of exactly, similar to how to a breathalyser will tell you how much alcohol is in someone's blood).
What's more, it appears that the company that manages to invent the breathalyser first looks set to make an absolute killing. Cannabix's rival, Lifeloc, which is also working on its own says that while a regular alcohol breathalyser sells for $300-400 in the States, a cannabis detector go for us as much as $2500-$3500.
What is slightly unfortunate though is that though the technology is getting there, scientists don't really know how much cannabis is bad for driving. The American National Highway Traffic Safety Administration apparently published a paper earlier this year saying that "cannabis impairs psychomotor skills, attention, lane tracking and cognitive function, but not enough is known about how much is needed to affect driving performance".
The difficulty is apparently that cannabis apparently affects people in different ways depending on whether they have smoked or ingested it - and whether they have taken it in combination with alcohol or other drugs too.