This November, several US states will vote whether to legalize marijuana use, joining more than 20 states that already allow some form of cannabis use. This has prompted a need for effective tools for police to determine on the spot whether people are driving under the influence. Stanford researchers have devised a potential solution, applying magnetic nanotechnology, previously used as a cancer screen, to create what could be the first practical roadside test for marijuana intoxication.
While police are trying out potential tools, no device currently on the market has been shown to quickly provide a precise measurement of a driver's marijuana intoxication as effectively as a breathalyzer gauges alcohol intoxication. THC, the drug's most potent psychoactive agent, is commonly screened for in laboratory blood or urine tests – not very helpful for an officer in the field. The Stanford device might function as a practical "potalyzer" because it can quickly detect not just the presence of THC in a person's saliva, but also measure its concentration.
http://phys.org/news/2016-09-potalyzer-roadside-saliva-marijuana-intoxication.html
[Source]: Stanford University
[Abstract]: Small Molecule Detection in Saliva Facilitates Portable Tests of Marijuana Abuse
(Score: 2) by dry on Sunday September 11 2016, @06:03AM
No, euphoria and the feeling that everything might go wrong. A heavy user is fine driving, perhaps a bit slow. Someone who isn't used to smoking is more likely to go dangerously slow while they're looking for somewhere to pull over and have a couple of coffees. The exception is when mixing with alcohol, where the pot may intensify the alcohol and if quite drunk, a good chance of falling asleep at the wheel, sorta like putting in 16 hour days and commuting.