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AAA Study: Blood THC Levels After Smoking Pot Are Useless In Defining 'Too High To Drive' (arstechnica.com)

Posted by BeauHD on from the illicit-substances dept.

An anonymous reader quotes a report from Ars Technica: Blood tests that try to quantify marijuana use are in fact useless at assessing how impaired a driver is, according to a study by the AAA Foundation for Traffic Safety. The study found that people with low blood amounts of THC -- or delta-9-tetrahydrocannabinol, the main psychoactive component of pot -- may still act as if they're really stoned. On the other hand, some people may have THC measurements off the charts yet still act normally. The finding is critical because several states have already set legal limits for the amount of THC a person can have in their blood while driving. AAA concluded that such limits are "arbitrary and unsupported by science, which could result in unsafe motorists going free and others being wrongfully convicted for impaired driving." The conclusion echoes that of other researchers that also noted no correlation between blood THC levels and impairment. Still, there is a need to deter people from smoking pot while driving, AAA argues, as it can impair driving. It recommends that until scientifically valid measures of impairments are put into place, law enforcement should use a combination of behavior and psychological tests to assess whether drivers who use marijuana are safe to drive.

9 of 455 comments (clear)

  1. How about... by Izuzan · · Score: 5, Funny

    The officer plays an Amy Schumer skit. If the person laughs they are to high to drive.....

    1. Re:How about... by AK+Marc · · Score: 5, Insightful

      But you have to draw the line somewhere.

      Yeah, you measure reflexes and decision making skills, and take them off the road if they are unsafe.

      But doing so would make AARP and voters mad, and we all know stoners don't bother to vote, so you make up arbitrary (and wrong) limits for chemicals, not related to the safety of the driver. Great system.

      --
      Learn to love Alaska
    2. Re: How about... by hairyfeet · · Score: 5, Interesting

      According to my cop customers they would rather have 10 potheads rather than one drunk on the road for one simple reason...stoners tend to drive too slow and speed is what kills. I've gotten to hear what a single drunk can do on the road...it ain't pretty as they tend to fly low and with their slow reaction time? Its a bloodbath waiting to happen. The potheads? They tend to find them doing 35 in a 55 and are too paranoid about their driving to do any stunts or try to outrun the cops like the drunks will often do.

      So if given the choice? I'd rather be a little late to an appointment because some pothead was driving slow than see some drunk weaving all over the road at 90 MPH + heading my way.

      --
      ACs don't waste your time replying, your posts are never seen by me.
    3. Re:How about... by TheGratefulNet · · Score: 5, Funny

      But doing so would make AARP and voters mad

      for those cases, there's static routing.

      (wait, wut?)

      --

      --
      "It is now safe to switch off your computer."
    4. Re:How about... by shaitand · · Score: 5, Informative


      Here is an article on the subject from the Washington Post:

      https://www.washingtonpost.com/news/the-watch/wp/2014/08/05/since-marijuana-legalization-highway-fatalities-in-colorado-are-at-near-historic-lows/

      Here is source data:

      https://www.codot.gov/library/traffic/safety-crash-data/fatal-crash-data-city-county

    5. Re: How about... by chihowa · · Score: 5, Insightful

      Lane discipline (or a lack thereof) is responsible for most accidents, which is why law enforcement's obsession with speeding is so obnoxious. The fact that police would rather be sitting on the side of the road clocking for speeders (because it's easy and hard to contest in court) and ignoring all of the inattentive drivers changing lanes without looking or signaling, failing to yield the passing lane and encouraging passing on the right, and so on is a damn shame.

      --
      If you want a vision of the future, imagine a youtube comments section scrolling - forever.
  2. Re:You need to set the cutoff somewhere by fustakrakich · · Score: 5, Funny

    Yeah well, I wish they would practice on their side of the road.

    --
    “He’s not deformed, he’s just drunk!”
  3. Re:You need to set the cutoff somewhere by rahvin112 · · Score: 5, Informative

    Yea, but blood alcohol limits had a LOT of science behind them before they became law. There is very good evidence showing reaction times are impaired a minimum of 50% at what are now legal blood limits even in the most tolerant drunk.

    The first person with the money to fight one of these blood THC levels is going to win because the limit is entirely arbitrary and there is in fact no evidence whatsoever that THC impairs reaction time. They'd have as much luck trying to convict someone for having whipped cream in the blood. You can thank that DEA level 1 classification for that as no one has been able to do any real research on cannabis. In time we will find out but the only reason the courts allowed blood alcohol to be used against you was because there was a TON of research and good hard science documenting the connection between blood alcohol and reaction time.

    The legislature can't make something legal to consume being in your blood illegal to drive unless they can demonstrate that it impairs your ability to drive. People have forgotten all the effort it took to get the courts to let blood alcohol content be actionable. Blood alcohol took almost a decade of court wrangling before it was eventually allowed as evidence of impairment. Hell maybe the supreme court will allow it because the most of the court loves jacked booted thugery but IMO the government should have to prove beyond a reasonable doubt that the substance impairs your driving ability to make it illegal to be on it while driving.

  4. Re:how about 0 by Anonymous Coward · · Score: 5, Informative

    Oh, wait, do you know why alcohol and marijuana have an effect on the body? It's because the body is receptive to it's presence. Have you thought about why the body is receptive to these substances? It's because the body produces these same substances on its own.

    This line of reasoning is flat out wrong in general. Plenty of receptors in the human body will react to many different molecules, including many that do not normally exist in the body but may have other molecules with similar shapes (or even just similar in one part that sticks out from the molecule).

    Ethanol is a pretty simple chemical and appears in a lot of places in biology, including human metabolism. However, the CB1 and CB2 receptors that respond to THC are not in the body because the body has THC, but because of endocannabinoids like AG2 and others. And the body doesn't react the same, as different endocannabinoids will affect the two different receptors in a different ratio and affect additional receptors that THC doesn't.