Testing drivers for cannabis impairment is something I’ve been thinking about just a little with legalizers in North Carolina and California. Some of this thinking is theirs.
One argument prohibitionists use against legalization of marijuana is that stoned drivers are a menace to everyone on the streets and roads. Marijuana is much less impairing than alcohol, but stoned driving worries people.
Figuring out which cannabis-consuming drivers make the roads unsafe is hard. With alcohol, breath and blood tests produce numerical results that allow “per se” determinations of intoxication: if the amount of alcohol in a driver’s system reaches .08 percent, or some bright-line numerical threshold, they’re guilty.
Finding a bright-line threshold for marijuana seemed like a way to find stoned drivers. Colorado, for instance, started out saying that 5 nanoliters per (milliliter?) of some THC chemical in blood were per se evidence of intoxicated driving. That was a political bone thrown to folks worried about the issue so as to get legalization passed.
Impaired driving is a battle NC NORML is fighting here, so they propose a five-minute roadside test for impairment, not involving bodily fluids.
To expand on that: Maybe some jurisdiction will say, “No conviction for cannabis-impaired driving without video evidence.” No video, no probable cause, no search, no arrest, no nothing.
The discussion below aims at that result.
If setting a bright line number of minutes (say five) the police can acquire roadside behavioral evidence of intoxication is worth pursuing, how might a five-minute rule interact with blood, oral fluid, or breath tests that detect active THC? (We can test hair and urine to show use, but they don’t show intoxication. they only detect non-psychoactive metabolites which don’t affect driving. Only blood, oral fluid, or breath tests detect active THC. o one even supposes a hair test shows intoxication.)
No conviction without failing both tests? (Presumably failing video-recorded the roadside behavioral test is ultimately a jury question – does the community think this person is impaired? Jury questions usually get plea-bargained away these days.) But what if someone shows no THC or alcohol or anything in bodily fluids or breath but does terribly on the behavioral test?
Anyway, if failure on both tests is required for a conviction, what’s the order of testing?
1. Police administer blood, oral fluid, or breath test and then, if it shows (enough?) THC have a go at the roadside behavioral test? How quickly do results come back from the tests?
2. Police administer a roadside behavioral test and if police say the suspect failed, then administer a blood, oral fluid, or breath test? And when the police say the driver failed the behavioral test, who oversees the police’s determination? A magistrate eventually? A magistrate on Zoom immediately? A jury (or prosecutor evaluating the case to present to a jury)?
Not my field . . .