Developing a viable cannabis breathalyzer | Hacker News Reader

Developing a viable cannabis breathalyzer

npr.org

28 pointsnewman8r51 comments

I would like to know how this works. THC is an oil or resin. For it to appear in your breath it has to be a vapor unless it is rolling out of your mouth as smoke. What is the vapor pressure of THC?

Here's an interesting tidbit:

The tricky thing about THC, however, is that it is a large and complex molecule unlike ethanol, the main compound in alcohol, which is relatively small and simple. According to Tom Bruno, a NIST research chemist and co-author of the new paper, the vapor pressure of the THC compound is “very, very low,” which makes it difficult to measure.

Bruno, along with fellow NIST researcher and lead author Tara Lovestead, found a way to skirt around this issue by measuring THC vapor pressure with a vapor-capturing technique called PLOT-cryo. It works by trapping vapors in a solid substance that coats the inside of a small tube. Because the tube is so small, Bruno said, the process is very efficient.

“You don’t have to collect a lot to get an analyzable result,” he remarked.

The PLOT-cryo device works like a very sensitive nose. It can sniff out different compounds from the air, and has been previously used to identify explosives as well as decaying flesh.

https://www.seeker.com/health/new-thc-finding-paves-the-way-...

Thank you that was interesting.

Why use less reliable proxies like breathalizers to gauge impairment when we now have the technology to measure it far more directly: convert traffic cop cars into mobile virtual reality driving simulators.

Put a gaming laptop in the trunk, and the DWI suspect behind the wheel with a VR headset on and let them drive through a couple of minutes of reasonably challenging simulated traffic. Let software come up with an objective score and store the simulated session as evidence if they fail.

Not only does this more directly measure impairment, it catches any cause of it, not just a particular substance. Virtual driving impairment will correlate with real driving impairment far better than parts per million of a molecule in the bloodstream.

Very difficult to prove that the simulation is an accurate and easy to grasp representation that holds up in a court.

You could put the judge and/or jury in VR headsets for the playback. They would see just what the defendant saw, in four dimensions. That's amazingly high fidelity, and the chain of evidence can be demonstrated with a checksum. Compared to judging the inner workings of a breathalyzer, that pretty good.

All that proves is they failed a simulation, not that they were under the influence. Burden of proof lies with the prosecution.

Seems like we should care more about driving impaired than about driving under the influence. The former is what we're trying to prevent by policing the later. You can be impaired without being under the influence, and under the influence without being significantly impaired.

I don't disagree, but I've had moments when I was a terrible driver: I was tired, I was pissed off, I was stressed, I had just received bad news, I was quitting nicotine, etc.

I've done that too, and I should have been busted for that too. Is it really better to risk other lives due to lack of sleep than from too many drinks? For some stranger's little kid in another car's back seat, impaired is impaired.

By that standard, that stranger could be arrested for careless driving because the child in their back seat was screaming for a juice box and they were allowing themselves to be distracted.

Failure to control a vehicle is a violation in the places I've lived. It applies regardless of circumstances. Ice patch, animal runs in front, screaming toddler, whatever the cause, you can still be arrested for it.

In which case you need no VR setup, as the event happened prior to the officer interaction. Most of what you described is a ticket, not an arrestable offense.

"You suck at video games, enjoy your DUI"

Honestly this sounds unreasonable.

It's an interesting idea, but the critical issue with it is that it's not illegal to be bad at driving. That could change, but that's how it is now.

Ah, but it's illegal to drive without a license and the test is a de facto driving test so you could make it so that if you fail it you won't get arrested but you get your license suspended on the spot.

Currently simulations aren't valid driving tests, so that entire section of law would have to change. Moreover, does any state do on-demand driving tests? Typically you set the appointment, not the state. Additionally Texas (I'm sure other states are similar) doesn't even "suspend on the spot" for DWIs (you have 40 days or more from the incident before the suspension is effective).

It'll illegal to drive dangerously though, surely. It's a test that removes the license to drive from those who can't drive properly, whether due to old age, eyesight, drugs, tiredness. Only self driving cars for you.

The tests for obtaining a license allow for multiple attempts, and are administered by officers trained for that job, and aren't based on a video game installed in a cruiser.

> It'll illegal to drive dangerously though, surely.

Yes, and for all but the worst offenses (say, 30+ miles over the speed limit) the penalty is merely a fine and points against your license.

If someone drives as if they are drunk, all the time, then I don't think they should have a license as they are clearly a danger to public health. On a similar note, the driving test for a license could include a run in the simulator to both test driving skills and establish a baseline for the test. Then the impairment could be measured as relative to that baseline.

I think it's a good idea.

> If someone drives as if they are drunk, all the time

This doesn't test "all the time". It only tests at one point in time.

States have entire sets of due process for removing someone's license due to medical reasons, etc. It's not on the spot based on a video game running from a laptop in an officer's trunk.

You're describing a fancy field sobriety test. There's a reason why those who fail field sobriety tests for alcohol are then asked for a breath sample (or when they refuse, a blood test)

A criminal defense lawyer would tell their clients to say in court they intentionally failed the test. (Burden of proof still lies with the prosecution) You can't be convicted for failing a test. You can only be convicted of being under the influence.

I read something (a legit study IIRC) that breathalyzers are not that accurate and if you don't hold them right can increase the BAC.

And NO you CAN be convicted for failing the test. The evidence is just a paper reciept from the breathalyzer.

The reason you choose the blood test is so you have evidence for later.

Also you will sober up a little while you wait.

To be clear, I mean no one is being convicted of failing a field sobriety test with no breathalyzer or blood BAC results.

I believe there was a case in Colorado where a medical Marijuana user had enough THC in their blood to be considered impaired but they were able to pass a field sobriety test so they weren't convicted of a DUI. The problem is that the amount of THC you need in your blood to impair you is different for every person so it's hard to develop a test for it. A driving simulator makes sense to me, though once you have a bunch of adrenaline kicking in and are totally focused on not going to jail, you may perform better than when you are relaxed in the comfort of your own car.

I have no idea legally how this would work, but is 'proving' impairment using your proposed method enough?

I would think the missing piece would still be linking impairment to a substance or condition that the driver knew about, but drove anyway. ...which is why a simple sobriety test is typically given before a Breathalyzer.

We should care more about getting incapable drivers to stop driving than detecting insobriety. We should want safety police, not morality police.

And strictly on the morality angle, I don't think driving drunk is more culpable than driving over tired or over angry. I find those things are about as easy to detect in myself as drunkenness.

Aside from the other issues, how do you expect your average police officer to handle that thing? You know they're not exactly the brightest people, right?

You tell the cop there's a problem with the simulator. He sits down. You point out that other driver just ran a red light. He gives chase on the simulator. You walk away. Sorted.

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It couldn’t be any worse than “specially trained officers” who are able to detect whether someone is high by thier mannerisms and arrest people who aren’t using anything.

https://www.11alive.com/article/news/investigations/the-drug...

That article is completely terrifying.

* I am much too much of a control freak to ever ever try drugs; no moral issue, just not for me.

* I have a drink of something on social occasion maybe once or twice a year, maybe not. Never got behind the wheel with even a sip of alcohol that day, let alone a glass, let alone anything approaching legal limit.

But I'm a klutz and I'm an introvert and I get nervous easily and I have NO idea what kind of "signs" my body would display in stressful situation with a police officer at night (my body an my brain have an uneasy working relationship - we mostly put up with each other:).

It is very literally my nightmare scenario to be accused by a police officer of intoxication where none exists. As much as I 100% support them, I'm probably more afraid of roadside checks than an actually inebriated person.

You can opt for the breathalyzer in most states, or they'll take you back to the office for a blood test.

If they take you to the office though they'll probably tow your car as a little extra bit of "fuck you" for exerting your rights

> You can opt for the breathalyzer in most states, or they'll take you back to the office for a blood test.

Please correct me if I'm wrong, but I was under the impression that if you opt out of a breathalyzer, they'll still charge you with a DUI and the courts will consider the breathalyzer refusal as an equivalent to being intoxicated.

Most (all?) states have the law written that if you refuse a breathalyzer it is an automatic license suspension. Depending on other evidence the state may press DUI charges.

Almost. Yes, you may still be charged. Yes, they may use the evidence of your refusal. As far as equivalence, no: the test itself is just one piece of evidence. Because refusal should ordinarily make it more difficult to prosecute DUI (for what is, comparable to the stop, a very small inconvenience), I think most states have an automatic license revocation penalty attached to it - usually around six months. Field sobriety tests (e.g. walk in a straight line), I think, are much less conclusive and do not have such requirement.

IANAL. Search for James Duane.

I was charged with a DWI a year ago. The case is still going through the court system.

I was pulled over for speeding, going 36 in 35. Yes I am serious, one mile over. But this wasn't surprising to me, I am a young Hispanic man so this is a normal occurrence for me.

First thing the officer said was "boy you look nervous". As most adults pulled over by police feel. I handed my license and insurance over. The license had my old address the insurance had my most recent. He asked? "Is this your address", "yes", "why is the address different?", "because I moved a couple of months ago and have not had time to drop by the DMV", "Step out of the car sir"

I refused the field sobriety test but offered a breathalyzer. I blew a .034, that's less than half the legal limit.

He asked more questions, I answered but was short and untalkative.

He ended up arresting me. I asked him, why if I blew half the legal. He gave me three reasons. One; I was speeding and that I must be intoxicated to not notice the speed signs, two; I was uncooperative and nervous and that's a sign of drug or alcohol use, and lastly I forgot my address so I was obviously impaired.

The latest offer from the prosecutor was moving my charge down to reckless driving with 1 year of probation. My lawyer says I can probably get it dismissed.

It has been the worst experience of my life. Thank god I have enough money to hire one of the best lawyers in town, for $7k btw.

Wow. That is awful. I'm sorry this happened to you, but thanks for sharing.

I must be missing something here. What are you actually charged with? DUI? How can that stand in court at all if the breathalyzer obviously proves you were under the limit?

In most US states, the 'legal limit' as detected with a breathalyzer is just a threshold that results in automatically being charged with a DUI/DWI if you exceed it. Blowing under the threshold doesn't provide you any kind of legal protection against being charged with a DUI/DWI.

Thanks. I thought it might be something like that.

So, in short, you should never blow, as that's never going to help you in any way?

In most states, refusing a breathalyzer test can cause suspension of your license, even if you are completely sober:

https://dui.findlaw.com/dui-arrests/can-i-refuse-a-breathaly...

Sadly, as with many things in our criminal justice system, the answer ends up being "hope that you're not prosecuted by mistake, and that you have enough money for a lawyer if you are".

A breathalyzer is just additional evidence. All the cops have to say is the defendant appeared to be on something.

The main thing you're missing is that the official story of the "justice system" is a fairytale. Once you're in its sights, their literal day job is to make your life hell. They get paid to do this and go home at 5, while you pay for and live it.

Presently its damages are externalities paid for by a fucked-up reverse lottery that we're all playing, most blissfully unaware. A significant fix would be to make the state responsible for the entire cost of all defense, days spent in a cage or court, any bail fees, and emotional distress. Having to pay compensation for their "mistakes" would obviously further increase the scumbags' perverse incentive to obtain convictions/pleas. But you'd hope after they had paid out enough for persecuting frivolous cases, budgetary constraints would necessitate a bit of downsizing.

Where did this happen?

> But I'm a klutz and I'm an introvert and I get nervous easily and I have NO idea what kind of "signs" my body would display in stressful situation with a police officer at night (my body an my brain have an uneasy working relationship - we mostly put up with each other:).

It was a little too hot to go for a run the other night, so I decided to go for whatever is between a jog and a power walk.

I was stopped by a cop, whose first words were, "What are you on? Pills? Uppers?" which continued on for about ten minutes along with accusations of trying to break into cars(?).

When you go out looking for a problem, and view those you're supposed to protect as dangerous, this is what happens.

The end result is that I'm wary to go for a run at night lest I get accused of crimes I didn't commit. So yes, if you're walking awkwardly or are a klutz, that means you're on drugs to some cops.

I am much more than a “klutz”, I have a mild neurological condition that you wouldn’t notice on first glance that affects my balance slightly. I’m always afraid of what would happen if I got stopped by the police. It doesn’t help that my disability also causes an excessive startle reaction (https://rarediseases.org/rare-diseases/hyperekplexia/).

One time I did get stopped by the police, they made me get out of the car and they saw my hand was balled up like I was about to hit him. I didn’t even think that I was showing signs of aggression - my hand is always balled up. Once I noticed the tension increasing, I immediately told him about my condition and my hand.

I am also Black, so I’m extra cautious. Of course, police are suppose to ask if you have a disability,but I’ve never put too much credence in the justice system.

https://www.jabatelaw.com/are-physical-disabilities-a-factor...

Exactly. The article even says as much. It simply detects if someone smoked something with THC in the last two hours. So there is no consideration for actual impairment?

My bullshit detector went off when the creator of the device said "this device has a lot of science in it."

Cannabis detection devices in Australia (NSW anyway, maybe VIC and other states) seem to have a detection window of a couple of days or more. So it's almost entirely moral policing operational over here. This would be an improvement on that.

My bullshit detector went off when the article said "the number of drivers involved in fatal crashes who tested positive for marijuana is up significantly" (a reference to Colorado). Duh, the overall percentage of the population smoking dope went up when legalized.

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