I've posted in the past about the difficulties of proving that a DUI suspect was impaired from using marijuana. See DUI Marijuana: Does Marijuana Impair Driving?, Identifying and Proving DUI Marijuana ("Stoned Driving"). I've also commented upon some states' simple solution to those difficulties: set arbitrary legal limits of marijuana in the blood — or simply outlaw driving with any trace of marijuana in the blood — regardless of lack of impairment ("zero tolerance"). See Driving + Trace of Marijuana = DUI.
This situation became even more difficult for the prosecution with the decision by the Supreme Court of the United States (SCOTUS) in Missouri vs. McNeely last year, requiring the police to obtain a warrant before drawing blood without the driver's consent. Since a breathalyzer can't measure or even detect marijuana, this left the police in a difficult situation.
Recently, I was interviewed at some length about this by a reporter from the American Bar Association Journal. Unlike many interviews I've given reporters, this one resulted in a very thorough and well-done article about the entire issue…
SCOTUS Ruling Could Complicate Laws on Impaired Driving
ABA Journal, April 2014 issue — In December 2012, Emily Sue Falkenstein of Renton, Wash., drove into a marked crosswalk where wheelchair-bound Gregory Ramirez, 48, was crossing with his 6-year-old niece in his lap. The crash broke his leg and his wheelchair, and it left the girl with bruises and scrapes, according to court papers.
The responding officer said Falkenstein's car smelled strongly of marijuana, but Falkenstein refused to take a blood test voluntarily. At the time, Washington law made blood draws mandatory for anyone arrested on charges of felony DUI, vehicular homicide or vehicular assault. A warrantless test eventually showed above-legal levels of alcohol and marijuana in Falkenstein's bloodstream.
Initially, Falkenstein faced felony charges of vehicular assault and reckless endangerment. But between the crash and her July 2013 plea deal, the U.S. Supreme Court decided Missouri v. McNeely. In that case, the court said officers may not take blood samples from drivers who refuse to provide them voluntarily, unless they have a warrant or some kind of "exigent circumstance." The rapid disappearance of alcohol from the bloodstream is not considered an exigent circumstance, the court said, though it might be a factor.
Because of the ruling, King County prosecutors decided not to use the results of the blood test as evidence, says Falkenstein's attorney, Philip Petersen of Auburn, Wash…
As in the Falkenstein case, McNeely could complicate intoxicated-driving prosecutions all over the country. According to federal Department of Transportation research, about 20 percent of drivers nationwide refuse to take a test when asked. But a long wait for a warrant may destroy key evidence by allowing the driver's body to metabolize alcohol or drugs.
Although the Supreme Court said this is not a per se exigent circumstance, it's still a problem for police agencies without the procedures or technologies to get a warrant quickly. That's especially so in the 15 states that expressly or implicitly decline to allow electronic warrant applications.
The wait may pose a special problem with drug-impaired driving, which is generally detected by a blood test. McNeely came down just months after Colorado and Washington legalized the possession and use of small amounts of marijuana. Prosecutors in those states expect a rise in marijuana-intoxicated driving; a marijuana "legal limit" was built into Washington's ballot initiative to address that concern.
Meanwhile, the rate of prescription drug abuse—particularly abuse of opioid or narcotic painkillers—has gone up dramatically since 1999, according to the Atlanta-based Centers for Disease Control and Prevention. In 2012, Kerry Kennedy (daughter of Robert F. Kennedy and ex-wife of New York Gov. Andrew Cuomo) was charged with DUI after an accident involving the sleep aid Ambien; she was acquitted Feb. 28.
Another controversial concern about McNeely is that it could invalidate the blood-testing requirements in states that imply consent laws, which say drivers consent to take tests by receiving driver's licenses. Because McNeely reaffirms that there's a constitutional right to refuse blood tests, some attorneys believe states won't be able to make waiving that right a condition of driving privileges. If courts agree, it could increase test refusals and thus make it harder to prove intoxicated driving.
"This means we can no longer sanction drivers who refuse blood testing by using that refusal as consciousness of guilt at trial. Nor, as was the case in Washington, can we mandate blood testing even in fatality cases," says Moses Garcia, a traffic safety prosecutor for the state of Washington. "This is a huge setback."
Lawyers on both sides say the wait time for a warrant is unlikely to cause many problems—at least not new problems. Leonard Stamm, a defense attorney who helped to write an amicus brief in McNeely for the National College for DUI Defense and the National Association of Criminal Defense Lawyers, says the new problems are arising in the few jurisdictions that were routinely taking blood without a warrant before McNeely. Some jurisdictions agreed with Missouri that alcohol dissipation creates a per se exigency; other states also had laws permitting warrantless draws in specific circumstances, such as after a crash.
In those areas, McNeely forced judges to consider whether the warrantless blood draw evidence, from cases pending while McNeely was decided, is admissible. Stamm of Greenbelt, Md., says the U.S. Park Police were routinely taking blood from test refusers without a warrant. He says the local judge who has the resulting cases has been granting or denying suppression motions based on whether each case has exigent circumstances. In other jurisdictions, he says, some judges have used the good-faith exception to the exclusionary rule.
In practice, there's a delay before almost any DUI test. The NCDD's brief said there are built-in delays even when a driver agrees to a roadside breath test, the quickest kind. The officer must read the implied consent advisory, sometimes permit a phone call to counsel, and observe the driver for 15 to 20 minutes to ensure the test results are not tainted.
For a test refusal, the NCDD brief said, it typically takes about two hours for police to get blood drawn. In an outlier case it cited, the blood draw took four hours from the time of the traffic stop. And in 21 states, the NCDD said, it "has long been the norm" to get a warrant after all or most test refusals…
Delays before the blood test are not generally fatal to an alcohol DUI case, even if the results show a driver is just under the legal limit, which is 0.08 percent blood-alcohol content in every state. That's because alcohol is metabolized at a predictable rate. Usually, the prosecution can bring in an expert to testify about the driver's likely blood-alcohol content at the time he or she was driving. (However, Garcia says that's not true when the alcohol level was low to start with, as well as when dealing with someone whose body metabolizes alcohol quickly.)
But the situation is more complicated with drugs. Drugs are not eliminated from the body in a predictable way, Garcia explains, so toxicologists can't extrapolate backward.
"With alcohol, you have a predictable metabolism," says Stamm. "But with the drugs you test for, you can't say that."
That's one reason the warrant requirement could exacerbate problems with proving drug DUIs. Garcia says future litigation might focus on whether this problem creates a per se exigency in drug DUI cases, even though McNeely found none for alcohol.
The extrapolation problem is part of a general lack of science helping prosecutors connect intoxication with impairment, DUI defense lawyers say. And that makes it harder to convict a drugged driver.
"I used to be a district attorney in LA," says Long Beach, Calif., defense attorney Lawrence Taylor, whose Drunk Driving Defense treatise was cited by Chief Justice John G. Roberts Jr. in his concurrence to McNeely. "When they filed a case, I would make darn sure that there was sufficient evidence independent of the blood test to convict, because the blood test is probably not going to help you a whole lot."
The trouble, Taylor says, is telling the jury what the test results mean. In some states, there are "zero tolerance" laws that permit juries to convict if a blood test shows the presence of any controlled substance. (Some of these laws apply only to certain drivers or certain drugs.) But the standard in the majority of states, including California, is whether the driver was under the influence or incapable of driving safely.
"Let's say [the blood test] comes back and says Xanax or amphetamines. OK, how much? Some figure. OK, what does that mean? That's where they don't know," Taylor says. "Because there are very few studies and specific drugs tested as to how they impact the ability to drive a car safely. So they can't translate it for a jury into whether the person is under the influence."
"They might have a statement from the defendant that 'I took such and such a drug at such and such a time,' " Stamm says. "They almost need that in order to prove those kinds of cases."
In these states, prosecutors might also have to show that any subjective evidence of impairment at the scene, such as stumbling or slurred speech, was actually caused by the drugs.
"Jurors want proof that the impairment is from the drugs and not from any other potential basis," says Garcia. "That means disproving chronic medical issues, injuries and tolerance—to name a few issues that arise in blood cases. When we are talking about prescription drugs, jurors also want us to prove the driver 'knew' about the harmful effects of the drug by some kind of warning."
This isn't to say that blood tests are completely useless, Garcia notes. Blood tests are an objective-seeming way to corroborate the officer's observations of things like bloodshot eyes.
"It tends to support the officer's observations," Garcia says, "even though he had no idea what the result was going to be."
Getting a warrant to test for marijuana presents a special challenge. First, marijuana is the most widely used illicit drug, according to the National Institutes of Health. It's also increasingly available, thanks to medical marijuana statutes in 20 states and Washington, D.C., and recreational legalization in Colorado and Washington.
There's some evidence that legalization has increased driving under the influence of marijuana in Washington state. After the state's December 2012 legalization date for possession, the Washington State Patrol's toxicology lab reported a 47.8 percent increase in DUI marijuana cases between January and July 2012 and from January to July 2013. Studies correlating traffic fatalities with marijuana have been less conclusive; one study found that fatalities actually went down after medical marijuana laws, and it suggested drivers were substituting marijuana for alcohol.
McNeely's warrant requirement could also complicate marijuana cases because THC, the active ingredient in marijuana, is eliminated from a user's bloodstream relatively quickly. By contrast, opiates like heroin or Oxycontin may take days to leave the bloodstream.
"A person who smokes marijuana can go from zero to well over 100 nanograms [of THC in the bloodstream] in a couple of minutes,” says Chris Halsor, a traffic safety resource prosecutor for the state of Colorado. “But as soon as they ingest it, it starts to dissipate out of the system precipitously. [The driver can be] under 20 or under 10 within an hour."
To address concerns about marijuana-impaired driving, states are increasingly trying to establish legal limits for blood-THC content like the 0.08 percent limit for alcohol. In the last 10 years, six states have set higher-than-zero legal limits for THC: Colorado, Nevada, Ohio, Pennsylvania, Washington and, most recently, Montana. In five of those states, prosecutors can use blood test evidence to show a per se violation. In Colorado, the evidence creates a "permissible inference" that the driver was unsafe, allowing the jury to consider other parts of the situation.
Garcia says regardless of dosage, studies show THC will drop below 5 to 6 nanograms per milliliter—Washington's per se limit is 5 ng—60 to 75 minutes after the smoker's last puff. If the THC level is below 2 ng, the state's toxicology lab won't even confirm it was there. This is an especially big problem, he says, because drivers generally stop smoking before they get into the car.
"In most cases … the 75-minute clock will have already started at the time of the stop," he says. "If officers could know when the driver last smoked, they could estimate how long they have before the evidence is completely lost."
As a result, time is important when taking a blood sample from an allegedly stoned driver—at least in the states with zero tolerance and per se rules. If there's a several-hour delay while the officer gets a warrant and takes the driver to a hospital, the blood evidence can be lost. And as with other drugs, it's difficult to extrapolate backward from a low test result.
In other states, however, marijuana-intoxicated driving is just as hard to prove with a blood test as other drugged driving. In fact, it may be harder in some ways. Colorado marijuana activist Mason Tvert, a spokesman for the Marijuana Policy Project, says scientists haven't been able to come up with a clear limit above which most or all drivers are unsafe. That's partly for the same reasons that the 0.08 alcohol limit isn't truly universal, he says: body weight and tolerance differ between drivers. But in addition, frequent marijuana use can leave a small amount of THC in the blood of sober people, throwing off test results.
That's one reason that, when considering a marijuana DUI legal limit for a sixth time, the Colorado legislature chose the permissible inference rule.
"Per se failed in Colorado multiple times because legislators could not accept the possibility that people who are not impaired could be automatically guilty of DUI," Tvert says. Furthermore, he says, there's some evidence that low levels of marijuana intoxication can actually make drivers safer. That's both because marijuana can reduce risk-taking behavior, and because drivers tend to recognize that they are impaired. In two studies, one by the Department of Transportation, subjects expressed a growing reluctance to drive as they got high—even on a closed course.
DUI defense attorney Taylor believes legislatures' solution to this will be more zero tolerance laws, which make it easier to convict without examining whether the driver was impaired. He says there's a movement in the California legislature toward such a law for marijuana. Tvert says a lot of elected officials have embraced a 5-nanogram limit, as seen in Colorado, Montana and Washington.