PHOENIX -- A prosecutor argued Tuesday there's nothing wrong with charging a motorist who smoked marijuana up to a month ago with driving while drugged.
In arguments to the Arizona Supreme Court, Susan Luder acknowledged that Carboxy-THC, a secondary metabolite of marijuana, can show up in blood tests for a month after someone has used the drug. And she did not dispute the concession of her own expert witness that the presence of that metabolite does not indicate someone is impaired.
But Luder, a deputy Maricopa County attorney, told the justices the Legislature is legally entitled to declare that a positive blood test for Carboxy-THC can be used to prosecute someone who, if convicted, can lose a driver's license for a year.
That contention drew questions from Chief Justice Rebecca Berch who wondered how far that logic can be stretched. She asked Luder whether her argument falls apart if it turns out that Carboxy-THC can be measured a year from someone smoking the drug -- or even five years.
Luder said she understands arguments about why it may not be fair to charge someone with drugged driving potentially 30 days after they used marijuana.
"But that's up to the Legislature to decide,' she said. And Luder said lawmakers are free to decide that any evidence of any metabolite that started out as marijuana -- and its psychoactive element THC -- is evidence of driving with drugs in the system.
Justice Robert Brutinel also questioned where the line is drawn. He said some otherwise illegal drugs eventually metabolize all the way down to water.
"Where do you draw the line to when the metabolite's no longer illegal?' he asked.
"It's hard to say,' Luder responded.
The case has significant implications beyond whether Hrach Shilgevorkyan can be charged with breaking the law.
It most immediately affects whether any of the 40,000 Arizonans who are legal medical marijuana users will effectively be banned from driving, given how long metabolite remains in the system. And it also makes potential criminals out of anyone else who drives and also has used marijuana in the last 30 days, including those who might be visiting from Washington or Colorado where recreational use of the drug is legal.
According to court records, Shilgevorkyan was stopped by a Maricopa County deputy sheriff in 2010 for speeding and making an unsafe lane change. The officer charged him with suspicion of driving under the influence and took him to the police station for a blood sample.
That sample, drawn about 90 minutes after he was stopped, showed the presence of Carboxy-THC. He was charged with violating a law which makes it a crime to driving while there is any illegal drug or its metabolite in the body.
A trial judge threw out the charge. But the Court of Appeals said the laws on impaired driving "must be interpreted broadly.'
Attorney Michael Alarid said that ruling effectively bans driving by anyone with the slightest amount of Carboxy-THC in the blood, "which is an absurd result.'
But Justice Scott Bales said the fact remains that anyone who tests positive for that drug had, in fact, used marijuana. And he said there is no way for police to "extrapolate backwards' to determine exactly when that person was impaired.
"If we don't know that, wouldn't it be reasonable for the Legislature to prohibit driving while you have Carboyx-THC in your system?' Bales asked.
The judge acknowledged that some people who test positive for Carboxy-THC never drove when they were impaired. But he said it may also be true that Hydroxy-THC, the primary metabolite which is psychoative, dissipates quickly into Carboxy-THC.
"And so you're going to miss some people who actually were under the influence at some point but by the time the sample's taken, all that's detectible is Carboxy,' Bales continued. "And if that's true -- if it's a choice between erring on over-inclusive or under-inclusive -- why isn't that ... a policy question for the Legislature rather than one for us?'
Alarid, however, said the only issue is whether there is specific evidence of impairment while someone is driving. And he said that labs can test for Hydroxy-THC, though he acknowledged most police agencies do not and simply rely on a positive test for Carboxy-THC.
"It casts the net too large,' Alarid said, saying it "criminalizes otherwise legal conduct.' Anyway, he argued, a ban on driving with Carboxy-THC in the blood is not rationally related to the purpose of the statute, which is to protect the public from "impaired' drivers.
Luder, however, rejected Alarid's contention that it's absurd to charge someone with Carboxy-THC in the system with driving under the influence of drugs. She said it is undisputed that metabolite is clearly a derivative of THC, the psychoactive element in marijuana.
"What would be absurd is to narrow the net that was cast by the Legislature when the statute was imposed,' she told the justices.
The justices gave no indication when they will rule.