THC driving limits could cause more innocent people to spend months in jail, attorney says

Categories: Marijuana, News

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On Monday, the Colorado Senate will take up HB 1261, a bill that sets THC driving limits at five nanograms per milliliter of blood -- a level to which many critics object. Indeed, even its sponsor, Representative Claire Levy, now thinks this number may be too strict. But attorney M. Colin Bresee says the problems run much deeper -- including test results that can take months to come back and prosecutors who don't understand them when they do.

As an example, Bresee shares a lab report from the Colorado Department of Public Health and Environment's Laboratory Services Division in regard to a client accused of driving under the influence of marijuana last year. Read it here:

As you can see, the blood sample was collected on September 4, 2010 and received by the lab on September 9. However, the report wasn't issued until November 15 -- more than two months later. And this type of delay is hardly unusual. Bresee notes that for another recent client, the span between collection and the report's appearance was nearly three months.

This could result in enormous hardship for an individual unable to post a DUI bond, which are typically set at around $1,000, Bresee says -- "and if you can't post a bond, you're not getting out of jail."

The document above also illustrates another issue that would be amplified by the passage of a THC driving limits bill, in Bresee's opinion. The results listed under the test name "Blood Cannabinoid Confirmation" read, "Delta-9-THC-COOH 30 ng/ml," which suggest that the driver in question had a THC level six times higher than the proposed intoxication limit. But that's not true, since the THC-COOH reading measures "the amount of THC that is stored in fatty tissue cells, but that isn't active," Bresee says.

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M. Colin Bresee.
Department of heath tests later showed that the amount of active THC in the driver's system (usually listed on forms as "Delta-9-THC," sans the COOH) was six nanograms. And a private test that Bresee says is more accurate than ones the state runs -- its methodology utilizes liquid, not gas, as does the CDPHE's lab -- registered the amount at just 1.5 nanograms.

Confused? So are many prosecutors, Bresee believes. They tend to assume that THC can be measured in the same way as alcohol, not realizing that the substance lingers in the body of a user in ways that will show up on tests but will not impede driving ability. "Here's the analogy I give," he says. "Imagine if someone got pulled over and had to do a blood test for an alcohol DUI, and not only did the test say how much alcohol you had in your system then, but also how much alcohol you've had in the past month. That's what it's like."

In one case set in a small eastern Colorado county, Bresee says it took him more than nine months to make a prosecutor understand the relevance of active versus inactive THC. And he thinks many people accused of driving under the influence of marijuana may have raised the white flag because they didn't register this distinction, either.

"If you didn't know the difference between THC and THC-COOH and your THC-COOH was over the five nanogram limit, you'd probably plead guilty, even if you weren't really impaired," he maintains, adding, "Prosecutors have literally made plea offers without even knowing the test results -- and people may be pleading guilty just to get out of jail, because it takes so long to get a test back."

In regard to the five nanogram limit, Bresee says, "the research I've read so far is very inconclusive. It seems like a convenient, arbitrary line, and the medical community is completely split on the line. So this seems more like politics -- that politicians are just picking a number -- than science.

"We created the medical marijuana laws first, and now we're trying to guess how to deal with it. We put the cart first, and now we're going to buy a horse. And when you get politics involved, I don't think people's constitutional rights are always the first concern."

More from our Marijuana archive: "THC driving limits: William Breathes is still (still!) waiting for blood test results."

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Holy shit are these mother fuckers for real... I bet the person who proposed this bill fucking drives drunk every night of the fuckin week on 60 dollar shots of whiskey.. fucking pathetic


How are they inocent if they are smoking an illegal substance in the first place?

Colorado Proud
Colorado Proud

The real problem here is that the voters of Colorado elected the people that are involved with this ridiculous wave of regulation. These folks that have personal feelings on these issues, with zero regards to the voters and will continue the wave until MMJ is so over-regulated no one wants to touch it. THAT IS WHAT THEY ARE DOING AND WILL CONTINUE TO DUE. Make sure when you go to the polls next time, we put the professional politicians, right-wingers, religious fanatics, fear mongers, and uneducated fools in the garbage where they belong, they're bad for such a fine state as ours.........we deserve better.....Peace....


Dear Respected Senators,

My name is [] and I am a professional chemist and Colorado citizen. A large part of my career has been working in pharmaceuticals under FDA regulations and body of knowledge. I also have an academic background in pharmacology, which is the study of drugs. I am writing in regard to the proposed THC/DUI bill because I am alarmed at the level of ignorance proliferating this item. My understanding is that Colorado is looking to say "me too" and pass a law that essentially says that if a person has 5 ng/mL THC metabolites in their blood then they are considered unfit to drive and if caught, they will become a criminal. My intent is to show you QUANTITATIVELY how ridiculously low 5 ng/mL really is. It appears many lawmakers are scientifically and mathematically challenged and it would be very embarrassing for you to go on the record as having blindly bought into this "me too" sensation invoked by other states without actually understanding what it represents. Pass this bill and you put a huge number of sober people in jail and cost the government an equally high amount of money that has no net effect on bettering society.

For the record, I do not condone driving under the influence of any intoxicant. Ever!

This may be long so thanks to you for reading it through and trying to learn. Understand pharmacology goes deep so this is generalized. The main points to cover include:

1) Concentration

2) Routes of administration and half-life

3) lipophilicity

4) Where 5 ng/mL really comes from

Please follow along...

1) Concentration

First, 5 ng/mL means five nanograms per milliliter That’s 5 one-billionths of a gram THC in about 25 drops of blood. Let's do a rough calculation to show what a fiasco this can be for 50% of Coloradoans. Ask yourself: How much THC is that in the body at once...white size dose? Does it make sense that 5ng/mL means someone is truly under the influence of cannabis? How high are they at 5 ng/mL?

We start with the question - How much blood in the body? An average value is 10 pints. A pint is also 473 milliliters (mL). So if you had 5 ng/mL then you would have 10 pints X 473 mL X 5 ng/mL THC = 23650 nanograms THC in the body. Well, 23650 nanograms is also 23.650 micrograms (millionths of a gram) , which is only .02365 milligrams (thousandths of a gram).

Some pharmacology books and other medical texts report a threshold dose of THC is about 20 milligrams. A threshold dose means the minimum amount of a drug required to create an effect in the patient.

So what concentration in the blood would THC be if someone smoked a threshold dose 20 mg? To answer that we consider a 20 mg intake and then divide by the blood volume to get the maximum possible blood concentration (lasting briefly). 20 mg / (10 pints X 473 mL per pint) = 4228 ng/mL.

To summarize, it takes a total of 0.02365 milligrams THC in your blood to fail a 5 ng/mL drug test (blood). But you need 20 milligrams before the drug will be pharmacologically active. That's a 100x difference. A 20 mg dose of THC, at maximum, will yield a blood concentration of 4228 ng/mL.

So a person is not really affected by THC until the blood concentration is well over about 4228 ng/mL. Even for a "lightweight" whose threshold dose is 10 mg instead of 20 mg, they would have 2114 ng/mL THC in their blood before even the slightest pharmacological effect is present. And what has been proposed is that 5 ng/mL is a number that will send people to jail.

2)Routes of administration and Half-Life

As you are well aware, drugs can be taken in different ways. For example, orally, which in the case of marijuana means eating the plant or eating a confection such as a cookie that has THC in it. One can also inhale a drug which means vaporizing the active ingredient and breathing it in - smoking. There is also sublingual, which means that the medicine is held in the mouth and this works well for aspirin and nitroglycerin for heart patients that can't swallow while having an attack. We also have IV which is by needle into the blood, and there is also rectally, a suppository.

Each method of getting a drug into the body has a very unique set of parameters for how the body absorbs the drug, what effect the drug will ultimately have, how long it takes for the dug to ever take effect, duration of the effects, etc. This is called pharmacokinetics and dynamics. Smoking cannabis is a very effective route of administration because the active THC is quickly absorbed into the blood. Smoking cannabis allows patients to "titrate" the dose they desire because the effects set in quickly. That means, once the patient has the desired effect they cease smoking any more because of the near real-time feedback. In contrast, orally consumed cannabis take a long time (hours) to be absorbed by the gut and get transferred to the blood via the intestines. This is why folks that eat cannabis sometime get a little too much and become uncomfortable for an hour or so, because with edible cannabis the dose cannot be titrated in real time but instead, the patient is committed to the dose they ingested. This is a side note but it is for this reason that the "increased marijuana potency" argument against decriminalization fails. When cannabis is more potent, someone smoking it will consume less because they titrate the dose to the desired effect. Essentially, more potent cannabis is safer because less combusted and particulate plant matter is inhaled, the only physical hazard associated with smoking cannabis.

The main point here is comparing routes of administration. When a drug is consumed orally (pills, ibuprofen, aspirin or a cannabis brownie) the drug must first pass through the intestines to get to the blood stream, then it must pass through the liver, only then does it make it to the brain. This is an important concept and it's called First Pass Metabolism. The digestive track rarely passes 100% of an orally consumed drug to the blood. Only a percentage of the drug makes it through the intestines. Then the liver 'filters' a percentage of the drug, which is converted to byproducts in an effort to secrete it through pee or poo. After going through all these filters it is finally circulated in the blood. After all the 'filters' the blood concentration would be less than the blood concentration of the same amount of cannabis being smoked. If you take medication orally you are taking more than is necessary. What that means is doctors and scientists know that the body will eliminate much of a drug and cause it to become inactive. So pills and tablets from pharmaceutical companies add extra active ingredients to account for First Pass Metabolism. This refers to "bioavailability". Some drugs may be 30% bioavailable so the pharmaceutical company may put 3 times more of the drug in the pill than the body needs for a desired effect. This is also why unfortunate folks out there have overdosed on pills by crushing and inhaling them (nasally). Inhalation does not involve First-Pass Metabolism so the subject essentially gets a higher dose than would be the case if they had swallowed the pill.

And it is for this reason that when folks eat cannabis, they generally need to eat more cannabis to get a certain effect, where smoking would require less cannabis to get the same effect. So someone that chooses to eat cookies as their primary means of consumption, instead of the less healthy smoking alternative, will likely have higher concentrations of THC metabolites in their blood. Furthermore, edible cannabis products usually incorporate butter, oil or some other fat (lipophilic) as a carrier. Eating cannabis with oils aids absorption in the gut, and it also appears to facilitates storage in the fat. Folks that choose to eat cannabis require not only more cannabis than the smokers, but they are more likely to store higher amounts of THC and/or metabolites in their fat. The non-smokers have an even higher bias against them should this law pass at 5 ng/mL.

This brings us to half-life. When a drug is taken there will be a point where the concentration of the drug in the blood will be maximum for a brief period, then it decreases over time. How long it takes for that maximum concentration to become half is called "half-life" For example, if you took an ibuprofen pill before work it would give a maximum blood concentration of say 10. If the blood concentration was 5 after an hour then we would say the half-life of ibuprofen is 1 hour. That lets us calculate how long the drugs will stay in the system and have an effect. We can see here that after two hours it will halve again. So at two hours there is only 1/4 of the concentration left. An hour later (3 hours after the maximum) it will be 1/8 as much and so on.

That may seem pointless but it is important to understand it in order understand lipophilicity and how it pertains to this bill.

3) Lipophilic means "fat-loving". In contrast, "hydrophilic" means water loving. In nature things are either water soluble or fat soluble, and occasionally both. A drug is generally either hydrophilic or lipophilic to some degree. This means some drugs in the body get stored for different periods of time depending on their chemical makeup. A hydrophilic drug (one that loves water) is a drug that does not like to be around fat, it will stay in a water-based system like blood or urine. Ultimately what this means is that if a drug is water-loving then the body will flush it very quickly. The drug is flushed by urine or defecation within hours or days. Many drugs are hydrophilic (water-loving). Examples include drugs such as caffeine, cocaine, aspirin, alcohol, yes alcohol. Conceptually, imagine that salt and sugar like to dissolve in water but never in olive oil (fat). The same is true of all drugs. Some will dissolve in water, some will dissolve in fat.

As it turns out there is a disgraceful bias against people that choose to consume the safer cannabis drug over harder drugs such as cocaine or alcohol. For drug tests, consumers of cocaine, alcohol and other hard drugs have the advantage over cannabis users in that the water-loving drugs eliminate from the body in a matter of hours to a few days. If you have a couple glasses of Cabernet the effects are gone in a few hours, although a chemist can detect it in your system long after the effects have worn off. But in a few days the chemist is at a loss because the body eliminated any detectable trace. It may be there in miniscule amounts at a level so low that the chemical instruments cannot see it (it is below the "detection limit").

Unfortunately, THC is a lipophilic drug. It likes fat and doesn't much like to be in water. If you mixed pure THC with water then the THC would float on top of the water as with oil and vinegar (vinegar is mostly water). With lipophilic drugs, they enter the blood stream and then as they travel around all the various organs and vessels very small amounts of the drug get absorbed into body fat. And we have fat everywhere, not just on the belly. What happens is THC gets thoroughly distributed in all the fat cells in the body and stored away. THC likes the fatty environment and will very slowly come out of the fat and into the water-based blood system over a long period of time. One way to accelerate getting rid of the THC that has been absorbed by fat is intense exercise (fat-burning) and a low fat diet - becoming lean.

So now that you know about the water-loving and fat-loving drugs you are primed to understand the unfair bias toward consumers of cannabis, and ultimately why the proposed 5 ng/mL is ignorantly and ridiculously low. This bias pushes a small percentage of the population to seek harder drugs in lieu of soft drugs like cannabis simply because they know they can pass a drug test within days of smoking crack or doing meth. Those are more toward the water-loving drugs end of the spectrum (hydrophilic).

Cannabis is known for it's lengthy residence time. I have personally seen cases in which a patient failed a drug test for cannabis SEVEN (7) weeks after cessation. Common literature data suggests 30-45 days before cannabis is fully eliminated from intermittent and regular cannabis users, such as with state-licensed medical marijuana patients.

You saw in 1) above that the blood concentration for someone that smokes a minimum amount of cannabis to achieve the ever slightest effect (threshold dose) needs to be 4228 ng/mL. Yet, there are people trying to pass a law that says if there is only 5 ng/mL present then this person is A) intoxicated or under the influence B) A criminal who will be wrongfully jailed and potentially forced to enroll in a treatment program for drug addicts. Five versus four thousand two hundred twenty eight. Seems kind ridiculous doesn't it?

Why is this such a problem? It is a huge problem because for example, a medical cannabis patient who uses cannabis say every other night after dinner to help with multiple sclerosis symptoms will no doubt fail a 5 ng/mL test when there is ZERO pharmacological (psychoactive) effect being exerted on that patient by the residual THC metabolites that are present at 5 ng/mL. The man or woman has to have over 4000 ng/mL to have psychoactivity. The problem is exacerbated for people with a high BMI (body mass index). Folks that have a little extra fat and don't regularly exercise to burn it off, these folks are especially susceptible to lipophilic drugs being stored in their fat. Furthermore, when a person with a little more body fat begins losing weight, what do you think happens? It causes the contents in the fat cells to be released into the blood a little faster and in higher amounts. This person may test higher for THC than someone that is lazy and gaining weight continually.

It is possible that a 200 lb. woman that smoked cannabis daily for a month and then quit, could very easily fail a 5 ng/mL limit days and weeks after the fact due to lipophilicity and fat-burning and. Remember, you're considering BILLIONTHS of a gram as criminal when in reality it takes at least one thousand time more to have a psychoactive effect.

4) Where does 5 ng/mL really come from (besides blindly copying other people's work, which they blindly copied...)?

As a chemist I do chemical testing. I use very sensitive analytical equipment that includes gas and liquid chromatographs like you would see on forensic TV shows like CSI or Bones. These are exactly what is used in forensic labs to test for drugs. When we talk about how low the instrument can detect we call that the "detection limit". Basically, we say that below the detection limit anything we measure is not accurate or reproducible. So if we want to measure pesticide residues on fruit and vegetables from Safeway, we can only reliably measure as low as the detection limit of the machine allows. Below that, we say the measurement is not accurate. Really, 5 ng/mL is nothing more than the generally accepted detection limit for testing of THC in body fluids. We can reliably measure down to 5 ng/mL THC in someone's blood and say that the number is valid. If the measured value of THC is lower than 5ng/mL then data is considered questionable and not legally defensible. It's that simple.

So consider the reality of the situation for a moment, please. Is your approach "...the forensic lab can measure it accurately down to 5 ng/mL so therefore if anyone has any detectable amount of THC in their blood, they are a criminal and we will immediately consider them impaired, and we will spend an incredible amount of state revenue convicting these people, taking their licenses, and making sure their lives are hell...". When the detection limit gets lower as technology improves, will you then say 1 ng/mL is now what we are going to use to determine you are impaired? Please consider use of a combination of logic and pharmacological data as opposed to magic numbers created by "me too" bills in other states. Consultants are everywhere. Please find some doctors that will verify these concepts more accurately for you and do this right, not the wrong way that middle America is blindly adopting. It's a very Reagan/Bush/Bush/Orwellian thing that's been proposed here. Think about it.

Sir, madam, I am appalled at the level of ignorance that proliferates this bill. I am totally on board with each of you in regard to making our streets and highways as safe as possible. I have complete disdain for drunk drivers. But with drunk drivers having killed so many people while stoned driver incidents pale in comparison (check the stats), why are you not targeting people with absurdly low levels of alcohol and alcohol byproducts (metabolites) in their blood. With alcohol being a CNS depressant and cannabis being classified a sedative-hypnotic, how can we allow people to be on the streets Sunday morning when they may have had a glass of wine on Saturday night? That Madam, Sir, is 5 ng/mL.

We say that 0.08% blood alcohol is "drunk driving". But in truth the analytical instruments used to determine blood content are far far more sensitive. They can also see down to the 5 ng/mL level. Why are you not trying to pass a bill that outlines ...if you consumed a few drinks Friday night, we still consider you drunk on Saturday night? Why?

There are many other similarly alarming points to cover but this at least presents the truth and absurdity of what is being proposed. Regardless of how you feel about cannabis users, transcend your personal feelings on the legalization argument and please do your duty to get educated on the facts and understand the implications of other people's ignorance an unwillingness to understand that which they discuss. This is not about zero tolerance, this is about a popular vote that is scientifically wrong. You cannot justify putting sober people in jail. Pass this bill at 5 ng/mL and you'll be putting a lot of medical marijuana users, laborers, professionals, executives, law enforcement and civil servants in jail who haven’t touched the stuff in days or weeks. It's time we are realistic.

Again - Pass this bill at 5 ng/mL and you'll be putting a lot of medical marijuana users in jail who haven’t touched the stuff in days or weeks. Think of this bill as the "Confirmation of Recent Possession Bill. Will there then be an amendment to the bill that says anyone with 5ng/mL THC can not only be prosecuted for DUI, but also for possession?

In all truth I was diagnosed this past summer with multiple sclerosis. I am a state-licensed medical marijuana patient. I don't drive under the influence of anything. You're telling me I cannot legally drive myself to the doctor the day after I have the medicine my well-respected neurologist has recommended. This does not sound like Colorado to me. I'm sorry, but it doesn’t sound like this place I've come to love so much.

With Utmost Respect,


What are we doing about this though? Are we just going to sit back and watch and get fucked over ? Shit.

Back to riding a bike and taking the bus for me!

Kathleen Chippi
Kathleen Chippi

The Dept of Health (CDPHE) has over 1,200 blood samples WAITING to be tested from the first 3 months of this year (some left over from last). 1,000 was the total number of tests done in the state 2 years ago.

Why the sudden increase of blood tests? Especially when deadly accidents are down? Does Claire Levy have any vested interests in drug testing, like the Gov of FL?

He transferred his ownership in a drug testing company to his wife and not a month ago he wrote a bill requiring all welfare recipients and state employee's to be drug tested. How convenient.

Kathleen Chippi
Kathleen Chippi

Deadly car accidents in Colorado are actually down last year. The only question I have is -- How does this DECREASE in deadly cars accidents relate to Colorado's mmj program?

Kathleen Chippi
Kathleen Chippi

NO study worldwide shows a DIRECT link with THC ONLY (active or inactive) and car accidents.

The problem causing this THC/driving 'problem' is called REEFER MADNESS.

Educate, don't OVER regulate!


I vote that people who actually know the topic be in charge of this. I am SO tired of ignorant people making the rules for the rest of us...this goes way beyond common sense.

I am not seeing information from the media about all the problems that cannabis users are causing. I see all the problems that drunks cause, what problem is trying to be fixed here?


If I am charged, I plan to have my attorney prove this is BS then take legal action against everyone involved to the extent that I am allowed. If they draw first blood, then I will retaliate. Use the law against me, and I will damn sure use the law against you!


I have had THC in me for a very long time and my driving record is flawless they can take that to the bank with there false lies .


Even tho I understand you I would advise you not to ever use retaliate in court you sure to lose but also if you do take them to court and fight them you can have your lawyer request you be allowed to also go after people who are protected by the law that's if you win but sometimes the judge will allow it then you can really stick it to them.I ain't a lawyer or acting like one all can do there research and this is only for educational purposes .O_O

Corey Donahue
Corey Donahue

Will, you most definitely are doing something, you sir a a rare journalist in world full of hacks. And Oo Monday 1:30 State Capitol Old Supreme Court Building Senate Judiciary Committee Hearing on HB-1261 be there.


The thing that worries me is the big database system they want to put into place so that police can see that we are MMJ patients when we are pulled over. Is that probable cause to force a blood draw and throw my ass in jail until the results are a couple of months?

These are the things that happen when confidentiality is removed from patient-doctor relationships...

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