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Submission + - With Pot Legal, Police Worry About Traffic Safety 13

Hugh Pickens writes writes: "AP reports that with Pot soon legal under state laws in Washington and Colorado, officials in both states are trying to figure out how to keep stoned drivers off the road as law enforcement officials wonder about whether the ability to buy or possess marijuana legally will bring about an increase of marijuana users on the roads. "We've had decades of studies and experience with alcohol," says Washington State Patrol spokesman Dan Coon. "Marijuana is new, so it's going to take some time to figure out how the courts and prosecutors are going to handle it. But the key is impairment: We will arrest drivers who drive impaired, whether it be drugs or alcohol." Marijuana can cause dizziness and slowed reaction time, and drivers are more likely to drift and swerve while they're high and Marijuana legalization activists agree people shouldn't smoke and drive. But setting a standard comparable to blood-alcohol limits has sparked intense disagreement because unlike portable breath tests for alcohol, there's no easily available way to determine whether someone is impaired from recent pot use. If scientists can't tell someone how much marijuana it will take for him or her to test over the threshold, how is the average pot user supposed to know? "A lot of effort has gone into the study of drugged driving and marijuana, because that is the most prevalent drug, but we are not nearly to the point where we are with alcohol," says Jeffrey P. Michael, the National Highway Traffic Safety Administration's impaired-driving director. "We don't know what level of marijuana impairs a driver.""
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With Pot Legal, Police Worry About Traffic Safety

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  • One of the first hits :

    Blood tests are a better detector of recent use, since they measure the active presence of THC in the system. Because they are invasive and difficult to administer, blood tests are used less frequently. They are typically used in investigations of accidents, injuries and DUIs, where they can give a useful indication of whether the subject was actually under the influence.

    Sounds pretty clear to me...

    • by dpilot ( 134227 )

      Clear, but invasive. You find the same thing with alcohol. A breathalyzer is considered non-invasive, so it can be done "in the field" with a lower level of probable cause. I don't know this for certain, but given that it involves taking a blood sample, I believe blood tests require the alleged drunk driver to be taken to a lab for testing, as opposed to in-the-field. I believe this also calls for a higher level of probable cause, including the breathalyzer result. One complication is that alcohol is r

      • With THC there is no equivalent to the quickie breathalyzer test, so blood testing would be required in all cases, and the whole probable cause thing becomes tougher. On the mitigating side, I believe THC persists longer than alcohol, so at least that aspect may be gone.

        Incorrect - []

        Mouth swab drug test information and results can be obtained within 15 minutes which leads to quick analysis and interpretation of the test results

        Granted, the test is limited by the fact it can detect substances taken as far back as 3-4 days, but it sure beats a blood test when it comes to invasive-ness and speed of result generation.

        • by mk1004 ( 2488060 )
          The only issue as far as I can tell is that the swab test only measures the presence of a drug, not how much. So you can't determine a level of impairment as you can with a BAC test.
          • The only issue as far as I can tell is that the swab test only measures the presence of a drug, not how much. So you can't determine a level of impairment as you can with a BAC test.

            "Determine level of impairment" would require a standard for how much THC is allowed to be present in the bloodstream to be "under the legal limit."

            Developing said standard would likely require years of R & D, not to mention the bureaucratic red tape that is intrinsic to this sort of thing.

            Treating it the same way we do alcohol, i.e. developing a standard measurement system, would be the right thing to do. Unfortunately, judging from the tone of the interviewees, I'm fairly certain they just want

  • Unfortunately, we've become too dependent on medical-ish types of tests to determine impairment. Since there's no viable analog to the breathalyzer to determine if someone is under the influence of marijuana on-scene, perhaps we should make greater use of field sobriety tests to determine impairment.

    Unfortunately, those tests are somewhat subjective. However, use of video recording during tests should provide for more objective analysis after the fact.

    The longevity of the chemical signatures of marijuana

Order and simplification are the first steps toward mastery of a subject -- the actual enemy is the unknown. -- Thomas Mann