Can THC Breathalyzer Tests Work for Law Enforcement?

A blow test for weed? Not shotgunning, no — a breathalyzer.

The first commercial THC breathalyzer, manufactured by Hound Labs, has been on the market since October 2023. The second one, a joint effort (couldn’t resist) between Cannabix Technologies and Omega Laboratories, is expected to launch in October 2024. And several startups are marketing THC breathalyzer prototypes as well.

Hound’s first customers were in the oil and gas, hospitality, and tourism industries, but the larger market for a THC breath test is law enforcement. Today, daily tokers outnumber daily drinkers, and alcohol and cannabis are the two most commonly detected substances in impaired drivers. Accordingly, highway patrol officers want a scientifically validated breath test to detect a driver’s recent THC consumption.

But is an exhale a reliable way to determine someone’s THC level? And is someone’s THC level the right way to ascertain a driver’s marijuana-induced impairment? If it is, how do you determine the THC equivalent of alcohol’s blood alcohol content (BAC) limit? Let’s investigate.

How do highway patrol officers currently determine whether a driver is high on weed?

Lest it appear otherwise, let’s clarify that THC breathalyzers are not widely used in law enforcement; they’re mostly used at job sites. And where they are used in law enforcement agencies, they’re still only in the piloting phase, not regarded as proven tech. Test results aren’t admissible in court and can’t be used as probable cause for arrest.

That said, the fact that they’re being tested in the field and are in ongoing design and development invites a pros-and-cons analysis, if not outright preemptive opposition.

Field Sobriety Tests

For detailed descriptions of field sobriety tests for marijuana, read “Marijuana Impairment FAQ” by the Office of Indigent Defense Services and “Marijuana-Impaired Driving: A Report to Congress” by the National Highway Traffic Safety Administration (NHTSA). To know how reliable the tests are, start with “Field Sobriety Tests and THC Levels Unreliable Indicators of Marijuana Intoxication (2021)” by the National Institute of Justice, an organization under the U.S. Department of Justice.

More recently, an August 2023 study in “JAMA Psychiatry” reported on a randomized clinical trial evaluating the use of field sobriety tests to determine whether a driver is under the influence of cannabis. The scientists’ conclusion:

“[W]hen administered by highly trained officers, FSTs [field sobriety tests] differentiated between individuals receiving THC vs placebo and driving abilities were associated with results of some FSTs. However, the high rate at which the participants receiving placebo failed to adequately perform FSTs and the high frequency that poor FST performance was suspected to be due to THC-related impairment suggest that FSTs, absent other indicators, may be insufficient to denote THC-specific impairment in drivers.”

And those didn’t even touch on the social justice issues associated with traffic stops and marijuana, which are quite ensnaring themselves.

Biofluid Tests

When permitted by law, and despite being notoriously prone to error, cops test the driver’s saliva, urine and/or blood for THC. The latter of these runs into issues with respect to the Fourth Amendment though. Some states require the cop to get a judge’s approval for a search warrant before obtaining a blood sample – and that’s just part of what makes it so difficult.

There’s also the fact that you need special training for phlebotomy (drawing blood). Also, you need to preserve the sample well in between obtaining it and getting to the nearest lab for processing. A traditional phlebotomy blood draw into vials or tubes for lab testing can’t remain at room temperature for more than eight hours. If getting that sample to a lab is the cop’s only priority for that shift, it’s reasonable to vouch for the sample’s integrity; if the cop has better things to do, the sample could be compromised.

Similarly, cops can’t legally force a driver to take a roadside piss test. Plus, any such test would need to be monitored to preserve sample integrity – a peepshow unlikely to be granted voluntarily. Plus, the THC in urine wouldn’t demonstrate the level of impairment at the time of driving, as it would mostly likely be a THC metabolite, not a THC molecule.

Testing positive results in a conviction for driving under the influence of drugs. That’s the case even if the THC is just lingering in the driver’s system inactively (as a metabolite) from cannabis consumption days or weeks prior. Conversely, a false negative result could let the driver go free even when their driving truly is impaired by recently consumed cannabis. So, biofluid testing for THC is a high-stakes game to play either way.

Can a breath test tell you how much THC is in someone’s body?

The far-fetched rationale given by THC breathalyzer marketers resembles carbon dating more than alcohol breath tests, really. A 2019 study in “Clinical Chemistry” found that THC levels in the breath of people who smoked cannabis fell by about 95% over three hours after use. From that finding, scientists concluded that sharply falling THC levels in breath could be unique to recent cannabis use.

So, if you compare the results of two breath tests conducted 60 minutes apart – and what a fun traffic stop that would be! – a huge drop in THC would tell you that the person had recently consumed cannabis. (Never mind that it doesn’t tell you whether the THC impaired their driving though.)

However, although convincing in theory at first blush, experts at the University of Colorado, Boulder, and the National Institute of Standards and Technology (NIST) aren’t falling for it. They don’t support using the foundational metric of how quickly THC clears breath to validate a person’s THC intoxication. Why not? Simple: “There isn’t enough data to state this conclusively.”

Justice Department scientist Frances Scott took that a step further when guesting on the department’s podcast “Justice Today” in early 2024. While explaining how hard it is to detect physical evidence of cannabis in breath, Scott said that any such evidence would disappear within an hour of consuming cannabis.

Does someone’s THC level tell you whether they’re unsafe to drive?

No. In fact, according to the Office of Indigent Defense Services, “Toxicologists are not able to provide expert testimony that a specific amount of THC present in a suspect’s blood (or other specimen) is definitively associated with being impaired by marijuana and render the driver unable to drive safely.”

A more eloquent response was put forth by researchers in the September 2021 “Frontiers in Psychiatry” article “Cannabis and Driving”:

“While legislators may wish for data showing straightforward relationships between blood THC levels and driving impairment that parallel those of alcohol, the widely different pharmacokinetic properties of the two substances, leading to a rapid fall in THC levels to a relatively steady, low baseline within ~20 min of an inhaled dose make this goal unrealistic.”

Even Hound’s president of employer solutions, Nina French, dismissed the idea. In an interview with Times Union, she is reported as having told the news outlet that “the test does not measure current impairment, as there is no standard for what cannabis impairment means, making such a test impossible.”

Carrying greater authority, aforementioned Justice Department scientist Scott said:

“[T]he THC concentration in the blood is not particularly well-correlated with impairment for driving. … maybe what we need to do is kind of get away from that idea that we can sort of have a number when it comes to marijuana and have that mean that you’re impaired. And it may get into some different types of measures than we’re used to doing. So maybe it’s not a blood measure or a breath measure.”

Scott went on to cite myriad factors that determine someone’s THC level (e.g., edibles vs. smoking, infrequent user vs. regular user). She also pointed out that the same THC level in two people can be present with very different symptoms for each person.

A 2021 report from the Justice Department found that:

“THC levels in biofluid were not reliable indicators of marijuana intoxication. Many of their study participants had significantly decreased cognitive and psychomotor functioning even when their blood, urine, and oral fluid contained low levels of THC. The researchers also observed that standardized field sobriety tests commonly used to detect driving under the influence of drugs or alcohol were not effective in detecting marijuana intoxication.”

In an article written for the American Bar Association by Judge Scott Pearson and Judge John Ginsteiner, the two judges explain:

“The disconnect between THC blood concentration and impairment results from the nature of THC, a lipophilic or fat-soluble substance. THC travels via the bloodstream to the brain and then processed through the endo-cannabinoid receptor system. The body pulls the THC out of the bloodstream and deposits it in the fatty tissue of the body, including the brain, which is composed largely of fat. The THC slowly leaches from fatty tissue as a metabolite to the body’s excretory system, resulting in elimination primarily through urine, sweat, the breath or the blood. Peak blood concentration of THC occurs prior to peak impairment. In short, unlike the very simple drug, alcohol, blood concentrations of THC and its metabolites fail to establish impairment at a particular time necessitating other proof or testimony demonstrating impairment from THC.”

The Office of Indigent Defense Services explains the role that our biology plays:

“[T]he chemical nature of THC causes it to move throughout the body in a complex manner. Since blood and brain are different tissues, physically separated from each other, blood concentrations of any drug can only estimate the brain concentration and thus impairment. … This low concentration of THC in the blood is not enough to cause the high concentration in the brain needed for impairment. Most blood tests show relatively low concentrations of THC. Since this THC in the blood can be from both past use as well as recent use, it is not possible to differentiate between the two or infer impairment. Impairment by THC is currently best detected from the symptoms of impairment.”

In a 2021 issue of “Traffic Injury Prevention,” researchers concluded their findings by shutting down any expectation of finding a THC limit:

“There appears to be a poor and inconsistent relationship between magnitude of impairment and THC concentrations in biological samples, meaning that per se limits cannot reliably discriminate between impaired from unimpaired drivers.”

What THC level should per se laws limit drivers to?

Could researchers create a scale for THC nanograms per milliliter (ng/mL) that parallels alcohol’s grams per deciliter (g/dL) BAC scale? That’s what you would need in order to draw a line between “safe to drive” and “unsafe to drive.”

The nationwide BAC limit since the 1990s has been 0.08 g/dL, although some states, counties or cities have a lower level. This limit was chosen because there’s a way to quantify a person’s alcohol intoxication, relative to symptoms demonstrated. The NHTSA summarizes alcohol’s predictable effects on driving as follows:

• 0.02 g/dL: Decline in visual functions (rapid tracking of a moving target), decline in ability to perform two tasks at the same time (divided attention)
• 0.05 g/dL: Reduced coordination, reduced ability to track moving objects, difficulty steering, reduced response to emergency driving situations
• 0.08 g/dL: Concentration, short-term memory loss, speed control, reduced information processing capability (e.g., signal detection, visual search), impaired perception
• 0.1 g/dL: Reduced ability to maintain lane position and brake appropriately
• 0.15 g/dL: Substantial impairment in vehicle control, attention to driving task, and in necessary visual and auditory information processing

By contrast, a ng/mL scale for THC’s effects is scientifically impossible to calculate. This means that the acceptable impairment level (weed’s equivalent of a BAC under 0.08 g/dL) for THC can’t be established. An analysis of the impact of combining toxicology testing with field sobriety tests, whose results were published in July 2023, explains:

“There is no reference method for identifying impairment following use of cannabis. Real-world driving impairment is the ultimate outcome of interest, but that is difficult to operationally define (crashes, high-risk behaviors, or slowed response to obstacles). Driving simulations, cognitive testing, and FSTs are all surrogates of impairment. Impairment was defined as the officer’s interpretation of the participant’s performance across all of the FSTs. Any participant with sufficient deficits on the FSTs that a trained police officer deemed them unsafe to drive was defined as being impaired. This definition was selected because, in a traffic stop, an officer’s observation of driving performance is the precipitating event, followed by FSTs and possibly a DRE exam. Unlike a traffic stop, in this controlled study officers did not observe participants’ driving and made a determination of impairment based only on observations during the FST examination. Results from the FSTs were combined with different cutoff blood or OF THC concentrations to classify participants as impaired, as was done previously.”

Even so, some U.S. states and other countries have established THC limits, usually 1 to 5 ng/mL. The most frequently referenced source for the argument to create a THC limit is the 2006 Driving under the Influence of Drugs, Alcohol and Medicines (DRUID) program. And this is despite those findings’ having been debunked repeatedly. But there are others too, of course.

A 2019 study by the University of British Columbia found that THC concentrations below 5 ng/mL did not appear to increase the risk of car accidents, whereas those above 5 ng/mL did. So, it’s not that there’s no basis for establishing a THC limit; it’s that the limits are case-specific and ultimately arbitrary. (For many, many more examples of studies championing THC limits that went on to be disproven, read this comprehensive literature review from Sage.)

All of that said, a noble effort was made by researchers for “Injury Epidemiology” in 2014 who created a framework for solving the drugged-driving problem. In their article “Establishing legal limits for driving under the influence of marijuana,” they cover every possible contingency to develop a system of per se laws. That was a decade ago though, and no such system is in place anywhere – not with that kind of intricacy anyhow. So, realism has yet to ease up on idealism when it comes to solving this.

Conclusion

It goes without saying that THC, as cannabis’ primary psychoactive cannabinoid, can induce effects that render someone unsafe to drive; that’s beyond debate, at least here anyhow. However, the one consistent finding in over a decade of international research is that a person’s THC level is not an indicator of whether that person has been rendered unsafe to drive.

Here and there, studies have chanced upon a convenient correlation between someone’s driving and their THC level, but those are outliers in this field of study. When you’ve got someone’s criminal record at stake, it’s unconscionable to hold them to the same standard of the one or two people whose test results validated one or two scientists’ thesis.

Maybe the question shouldn’t be, “How much THC does that bad driver have?” Maybe the question should be, “How can we better train cops to recognize signs of marijuana impairment, such that we can trust their judgment in the absence of precise testing?”

If the preponderance of evidence says that proof of cannabis-induced impairment derives from intuition, then let’s work with what reality is throwing in our faces over and over: Come up with a field sobriety test that’s specific to THC impairment. No electronics. No piss, blood or spit. Just a cop’s cognitive ability – refined by training yet to be developed – to arrive at a logically sound deduction concerning someone’s cannabis-related impairment. It’s certainly worth considering.

Kathleen Hearons is a writer, editor, linguist and voice over actor from Los Angeles. She specializes in creative writing and research-intensive analysis and reporting.  

 

 

 

Sources and Suggested Reading

“A History of Drunk Driving Laws.” This Day in Wine History. Accessed Sept. 27, 2024. https://thisdayinwinehistory.com/a-history-of-drunk-driving-laws/.

“Alcohol and drugs.” Insurance Institute for Highway Safety and Highway Loss Data Institute. Last updated July 2024. Accessed Sept. 28, 2024. https://www.iihs.org/topics/alcohol-and-drugs.

“Alcohol, Other Drug, and Multiple Drug Use Among Drivers.” National Transportation Safety Board. Dec. 13, 2022. Accessed Sept. 28, 2024. https://www.ntsb.gov/safety/safety-studies/Documents/SRR2202.pdf.

Arkell, Thomas R., Danielle McCartney and Ian S. McGregor. “Medical cannabis and driving.” Australian Journal of General Practice, Vol. 50, Issue 6 (June 2021). doi:10.31128/AJGP-02-21-5840. Accessed Sept. 27, 2024. https://www1.racgp.org.au/ajgp/2021/june/medical-cannabis-and-driving.

Arkell, Thomas R., Frederick Vinckenbosch and Richard C. Kevin. “Effect of Cannabidiol and Δ9-Tetrahydrocannabinol on Driving Performance: A Randomized Clinical Trial.” JAMA, Vol. 324, Issue 21 (December 2020): 2177-2186. doi:10.1001/jama.2020.21218. Accessed Sept. 27, 2024. https://jamanetwork.com/journals/jama/fullarticle/2773562.

Arkell, Thomas R., Tory R. Spindle, Richard C. Kevin, Ryan Vandrey and Iain S. McGregor. “The failings of per se limits to detect cannabis-induced driving impairment: Results from a simulated driving study.” Traffic Injury Prevention, Vol. 22, Issue 2 (2021): 102-107. doi:10.1080/15389588.2020.1851685. Accessed Sept. 28, 2024. https://www.tandfonline.com/doi/full/10.1080/15389588.2020.1851685.

Asbridge, Mark, Jill A. Hayden and Jennifer L. Cartwright. “Acute cannabis consumption and motor vehicle collision risk: systematic review of observational studies and meta-analysis.” BMJ (Clinical research ed.), Vol. 344, Art. e536 (February 2012). doi:10.1136/bmj.e536. Accessed Sept. 28, 2024. https://pubmed.ncbi.nlm.nih.gov/22323502/.

Aussem, Pat. “Marijuana and Driving: How risky is it?.” Partnership to End Addiction. Last updated August 2024. Accessed Sept. 28, 2024. https://drugfree.org/article/marijuana-and-driving/.

“BAC Legal Limits in Different States, Counties, & Cities.” American Addiction Centers. Accessed Sept. 28, 2024. https://alcohol.org/dui/bac-limits/.

Benedetti, Marco H., et al. “Demographic and policy-based differences in behaviors and attitudes towards driving after marijuana use: an analysis of the 2013–2017 Traffic Safety Culture Index.” BMC Research Notes, Vol. 14, Art. 226 (2021). Accessed Sept. 28, 2024. https://bmcresnotes.biomedcentral.com/articles/10.1186/s13104-021-05643-3.

Brubacher, Jeffrey R., et al. “Cannabis Legalization and Detection of Tetrahydrocannabinol in Injured Drivers.” The New England Journal of Medicine, Vol. 386, No. 2 (January 2022): 148-156. doi:10.1056/NEJMsa2109371. Accessed Sept. 28, 2024. https://www.nejm.org/doi/10.1056/NEJMsa2109371.

Burke, Molly. “‘Marijuana breathalyzer’ hopes to help workplace screening.” Times Union. Last updated Oct. 10, 2023. Accessed Sept. 27, 2024. https://www.timesunion.com/capitol/article/biotech-company-unveils-marijuana-breathalyzer-18414791.php.

“Cannabis & Driving.” AAA. Accessed Sept. 28, 2024. https://exchange.aaa.com/safety/substance-impaired-driving/cannabis-driving/.

“Cannabis and Driving.” Centers for Disease Control and Prevention. Feb. 22, 2024. Accessed Sept. 28, 2024. https://www.cdc.gov/cannabis/health-effects/driving.html?CDC_AAref_Val=https://www.cdc.gov/marijuana/health-effects/driving.html.

“Cannabis & Driving.” International Council on Alcohol, Drugs & Traffic Safety. Accessed Sept. 28, 2024. https://www.rsa.ie/docs/default-source/road-safety/campaigns/icadts-cannabis-2-recent-experimental-evidence.pdf?sfvrsn=b913fa69_3.

“Cannabix Technologies to Present Marijuana Breathalyzer Technology at International Association for Chemical Testing (IACT) Conference in California.” Cannabix Technologies. April 22, 2024. Accessed Sept. 27, 2024. https://cannabixtechnologies.com/investors/news-releases/cannabix-technologies-to-present-marijuana-breathalyzer-technology-at-international-association-for-chemical-testing-iact/.

Caulkins, Jonathan P. “Changes in self-reported cannabis use in the United States from 1979 to 2022.” Addiction, Vol. 119, Issue 9 (May 2024): 1648-1652. https://doi.org/10.1111/add.16519. https://onlinelibrary.wiley.com/doi/full/10.1111/add.16519.

Chihuri, Stanford, and Guohua Li. “Direct and indirect effects of marijuana use on the risk of fatal 2-vehicle crash initiation.” Injury Epidemiology, Vol. 7, Article 49 (2020). Accessed Sept. 28, 2024. https://injepijournal.biomedcentral.com/articles/10.1186/s40621-020-00276-9.

Chow, Robert M., et al. “Driving Under the Influence of Cannabis: A Framework for Future Policy.” Anesthesia & Analgesia, Vol. 128, Issue 6 (June 2019): 1300-1308. doi:10.1213/ANE.0000000000003575. Accessed Sept. 28, 2024. https://journals.lww.com/anesthesia-analgesia/fulltext/2019/06000/driving_under_the_influence_of_cannabis__a.43.aspx.

“Does cannabis use affect driving?” in “Cannabis.” National Institute on Drug Abuse. Accessed Sept. 28, 2024. https://nida.nih.gov/research-topics/cannabis#cannabis-driving.

Dresden, Danielle. “What to know about the breathalyzer test.” Medical News Today. Last updated Feb. 15, 2023. Accessed Sept. 27, 2024. https://www.medicalnewstoday.com/articles/breathalyzer-test.

“Drug Impaired Driving.” Governors Highway Safety Administration. Last updated January 2024. Accessed Sept. 28, 2024. https://www.ghsa.org/state-laws/issues/drug%20impaired%20driving.

“Drug-Impaired Driving.” National Highway Traffic Safety Administration, U.S. Department of Transportation. Accessed Sept. 28, 2024. https://www.nhtsa.gov/risky-driving/drug-impaired-driving.

“Drugged Driving.” Office of Traffic Safety, Minnesota Department of Public Safety. Accessed Sept. 27, 2024. https://dps.mn.gov/divisions/ots/drugged-driving/Pages/default.aspx.

“Drugged Driving: Marijuana-Impaired Driving.” National Conference of State Legislatures. Last updated March 27, 2024. Accessed Sept. 27, 2024. https://www.ncsl.org/transportation/drugged-driving-marijuana-impaired-driving.

“Drugged Driving FAQs.” Colorado Department of Transportation. Accessed Sept. 27, 2024. https://www.codot.gov/safety/impaired-driving/druggeddriving/faqs.

“Drunk Driving.” National Highway Traffic Safety Administration, U.S. Department of Transportation. Accessed Sept. 27, 2024. https://www.nhtsa.gov/risky-driving/drunk-driving.

Ferguson, Dana. “Coming soon to Minnesota roadways: Oral tests for marijuana, other drug use by drivers.” MPR News. Jan. 5, 2024. Accessed Sept. 27, 2024. https://www.mprnews.org/story/2024/01/05/coming-soon-to-minnesota-roadways-oral-tests-for-marijuana-other-drug-use-by-drivers.

“Field Sobriety Tests and THC Levels Unreliable Indicators of Marijuana Intoxication.” National Institute of Justice, Office of Justice Programs, U.S. Department of Justice. April 5, 2021. Accessed Sept. 27, 2024. https://nij.ojp.gov/topics/articles/field-sobriety-tests-and-thc-levels-unreliable-indicators-marijuana-intoxication.

Fierro, Inmaculada Fierro, Juan Carlos González-Luque and F. Javier Álvarez. “The relationship between observed signs of impairment and THC concentration in oral fluid.” Drug and Alcohol Dependence, Vol. 144 (November 2014): 231-238. doi:10.1016/j.drugalcdep.2014.09.770. Accessed Sept. 27, 2024. https://www.sciencedirect.com/science/article/abs/pii/S0376871614018328?via%3Dihub.

Fitzgerald, Robert L., et al. “Driving Under the Influence of Cannabis: Impact of Combining Toxicology Testing with Field Sobriety Tests.” Clinical Chemistry, Vol. 69, Iss. 7 (July 2023): 724-733. doi:10.1093/clinchem/hvad054. Accessed Sept. 27, 2024. https://academic.oup.com/clinchem/article/69/7/724/7179849#google_vignette.

Gallion, Bailey. “With Ohio recreational marijuana sales approaching, detecting DUIs remains a challenge.” The Columbus Dispatch. Last updated July 26, 2024. Accessed Sept. 27, 2024. https://www.dispatch.com/story/news/crime/2024/07/26/recreational-weed-is-coming-to-ohio-but-proving-duis-poses-challenge/74511619007/.

Goodman, Lawrence. “NIST’s New Hemp Reference Material Will Help Ensure Accurate Cannabis Measurements.” National Institute of Standards and Technology, U.S. Department of Commerce. July 8, 2024. Accessed Sept. 27, 2024. https://www.nist.gov/news-events/news/2024/07/nists-new-hemp-reference-material-will-help-ensure-accurate-cannabis.

Goodman, Lawrence. “NIST Researchers to Test New Approach for Detecting Cannabis in Breath.” National Institute of Standards and Technology, U.S. Department of Commerce. Last updated Aug. 26, 2024. Accessed Sept. 27, 2024. https://www.nist.gov/news-events/news/2024/08/nist-researchers-test-new-approach-detecting-cannabis-breath.

Hartman, Rebecca L., and Marilyn A. Huestis. “Cannabis Effects on Driving Skills.” Clinical Chemistry, Vol. 59, Issue 3 (2013): 478-92. doi:10.1373/clinchem.2012.194381. Accessed Sept. 28, 2024. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3836260/.

Hearons, Kathleen. “Drug Test with False Positive? Just Say ‘No.’” Head Magazine. Accessed Sept. 28, 2024. https://headmagazine.com/drug-test-with-false-positive-just-say-no/.

Hearons, Kathleen. “Is Drug-Testing Sewage a Good Way to Determine a City’s Weed Habits?.” Head Magazine. Accessed Sept. 28, 2024. https://headmagazine.com/is-drug-testing-sewage-a-good-way-to-determine-a-citys-weed-habits/.

Hearons, Kathleen. “Marijuana and the Americans with Disabilities Act: How Does the Controlled Substances Act Affect Disabled Americans?.” Head Magazine. Accessed Sept. 28, 2024. https://headmagazine.com/marijuana-and-the-americans-with-disabilities-act-how-does-the-controlled-substances-act-affect-disabled-americans/.

Hearons, Kathleen. “President Biden’s Weed Pardon: What You Need to Know.” Head Magazine. Accessed Sept. 28, 2024. https://headmagazine.com/president-bidens-weed-pardon-what-you-need-to-know/.

Hearons, Kathleen. “The Illogic of Illegal Weed: A Comprehensive Analysis.” Head Magazine. Accessed Sept. 28, 2024. https://headmagazine.com/the-illogic-of-illegal-weed-a-comprehensive-analysis/.

HOUND® CANNABIS BREATHALYZER. Hound Labs, Inc. Accessed Sept. 27, 2024. https://houndlabs.com/product-overview/.

“Hound Labs Ships the First Commercial Cannabis Breathalyzer.” Hound Labs, Inc. Oct. 10, 2023. Accessed Sept. 28, 2024. https://houndlabs.com/2023/10/10/hound-labs-ships-the-first-commercial-cannabis-breathalyzer/.

“Know Your Limit – Cannabis.” Northwestern University. Accessed Sept. 28, 2024. https://www.northwestern.edu/aodresources/harm-reduction/know-your-limit-cannabis.html.

Knudsen, Jennifer, Courtney Popp, Deena Ryerson and Ashley Schluck. “Marijuana-Impaired DUI: Using Research to Prove Your Case.” Colorado District Attorneys’ Council, Oregon Department of Justice and Wyoming Highway Safety Program. Accessed Sept. 28, 2024. https://ag.nv.gov/uploadedFiles/agnvgov/Content/Issues/TSRP%20MJ%20Workgroup%20Research%20Handout%20-%20updated.pdf.

Lee, Josh. “New Tests Needed for Drugged Driving.” The Paper. March 6, 2024. Accessed Sept. 27, 2024. https://abq.news/2024/03/new-tests-needed-for-drugged-driving/.

Li, Mu-Chen. “Marijuana use and motor vehicle crashes.” Epidemiology Review, Vo. 34, Issue 1 (2012): 65-72. doi:10.1093/epirev/mxr017. Accessed Sept. 28, 2024. https://pubmed.ncbi.nlm.nih.gov/21976636/.

Lynch, Kara L., Y. Ruben Luo, Shirin Hooshfar and Cassandra Yun. “Correlation of Breath and Blood Δ9-Tetrahydrocannabinol Concentrations and Release Kinetics Following Controlled Administration of Smoked Cannabis.” Clinical Chemistry, Vol. 65, Issue 9 (September 2019): 1171-1179. doi:10.1373/clinchem.2019.304501. Accessed Sept. 29, 2024. https://academic.oup.com/clinchem/article/65/9/1171/5608513.

Marcotte, Thomas D., et al. “Driving Performance and Cannabis Users’ Perception of Safety: A Randomized Clinical Trial.” JAMA Psychiatry, Vol. 79, Issue 3 (2022): 201-209. doi:10.1001/jamapsychiatry.2021.4037. Accessed Sept. 28, 2024. https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2788264.

Marcotte, Thomas D., et al. “Evaluation of Field Sobriety Tests for Identifying Drivers Under the Influence of Cannabis: A Randomized Clinical Trial.” JAMA Psychiatry, Vol. 80, Issue 9 (2023): 914-923. doi:10.1001/jamapsychiatry.2023.2345. Accessed Sept. 29, 2024. https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2807719.

“Marijuana and DUI Laws.” Marijuana Policy Project. Accessed Sept. 28, 2024. https://www.mpp.org/issues/criminal-justice/marijuana-and-dui-laws/.

“Marijuana & OUI: Driving While High in Massachusetts.” Law Office of Patrick J. Murphy. Accessed Sept. 28, 2024. https://www.bostoncriminaldefenselawyers.com/practice-areas/how-an-experienced-lawyer-can-help-you-fight-oui-dui-dwi-charges/marijuana-oui-driving-while-high-in-massachusetts/.

“Marijuana Impairment FAQ.” IDS Forensic Resources, Office of Indigent Defense Services. Nov. 9, 2021. Accessed Sept. 27, 2024. https://www.ncids.org/2021/marijuana-impairment-faq/.

“Marijuana vs. Alcohol: What’s The Difference in Impaired Driving?.” Hartford HealthCare Institute of Living. Jan. 14, 2022. Accessed Sept. 27, 2024. https://instituteofliving.org/health-wellness/news/newsroom-detail?articleId=38108&publicid=472.

“Marijuana-Impaired Driving: A Report to Congress.” National Highway Traffic Safety Administration, U.S. Department of Transportation. July 2017. Accessed Sept. 28, 2024. https://www.nhtsa.gov/sites/nhtsa.gov/files/documents/812440-marijuana-impaired-driving-report-to-congress.pdf.

Marsh, Allie. “What is the difference between active THC and the metabolite of marijuana?.” The Buzbee Law Firm. Last updated April 4, 2023. Accessed Sept. 29, 2024. https://www.ryanpigglaw.com/post/what-is-the-difference-between-active-thc-and-the-metabolite-of-marijuana.

Marshall, Lisa. “A reliable cannabis breathalyzer? Possible, but not easy.” CU Boulder Today, University of Colorado, Boulder. Sept. 11, 2023. Accessed Sept. 27, 2024. https://www.colorado.edu/today/2023/09/11/reliable-cannabis-breathalyzer-possible-not-easy.

McCartney, Danielle, Thomas R. Arkell, Christopher Irwin, Richard C. Kevin and Iain S. McGregor. “Are blood and oral fluid Δ9-tetrahydrocannabinol (THC) and metabolite concentrations related to impairment? A meta-regression analysis.” Neuroscience & Biobehavioral Reviews, Vol. 134, Art. 104433 (March 2022). Accessed Sept. 28, 2024. https://www.sciencedirect.com/science/article/pii/S0149763421004978?via%3Dihub.

Miller, Naseem S. “Driving under the influence of marijuana: An explainer and research roundup.” The Journalist’s Resource. July 29, 2024. Accessed Sept. 27, 2024. https://journalistsresource.org/health/marijuana-driving/.

Mlynaryk, Nicole, et al. “Can Field Sobriety Tests Identify Drivers Under the Influence of Cannabis?.” UC San Diego Today, University of California, San Diego. Aug. 2, 2023. Accessed Sept. 28, 2024. https://today.ucsd.edu/story/can-field-sobriety-tests-identify-drivers-under-the-influence-of-cannabis.

Nieto-Munoz, Sophie. “Bill would force drivers to provide blood sample if suspected of driving high: Critics say measure would disproportionately harm Black, Latino drivers.” New Jersey Monitor. Feb. 29, 2024. Accessed Sept. 27, 2024. https://newjerseymonitor.com/2024/02/29/bill-would-force-drivers-to-provide-blood-sample-if-suspected-of-driving-high/.

Nuber, Christa. “What is the shelf life and journey of a blood sample?.” Neoteryx. Oct. 19, 2020. Accessed Sept. 29, 2024. https://www.neoteryx.com/microsampling-blog/what-is-the-shelf-life-of-blood-and-journey-of-a-blood-sample.

Origenes, Alexandra N., Sarah A. White, Emma E. McGinty and Jon S. Vernick. “State Driving Under the Influence of Drugs Laws.” Journal of Law, Medicine & Ethics, Vol. 52, Issue 1 (2023). Accessed Sept. 28, 2024. https://www.cambridge.org/core/journals/journal-of-law-medicine-and-ethics/article/state-driving-under-the-influence-of-drugs-laws/7444EAF8C6746E3D0458B8FBB7B029A6.

Pearlson, Godfrey D., Michael C. Stevens and Deepak Cyril D’Souza. “Cannabis and Driving.” Frontiers in Psychiatry, Vol. 12, Art. 689444 (September 2021). doi:10.3389/fpsyt.2021.689444. Accessed Sept. 27, 2024. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8499672/.

Pearson, Scott, and John Grinsteiner. “Testing Challenges: No BAC for THC.” American Bar Association. Aug. 12, 2024. Accessed Sept. 27, 2024. https://www.americanbar.org/groups/judicial/publications/judicial_division_record_home/highway-to-justice/testing-challenges-no-bac-for-thc/.

Perkins, Daniel, et al. “Medicinal cannabis and driving: the intersection of health and road safety policy.” International Journal of Drug Policy, Vol. 97, Art. 103307 (November 2021). doi:10.1016/j.drugpo.2021.103307. Accessed Sept. 28, 2024. https://www.sciencedirect.com/science/article/pii/S0955395921002127.

Sevigny, Eric L. “Cannabis and driving ability.” Current Opinion in Psychology, Vol. 38 (April 2021): 75-79. doi:10.1016/j.copsyc.2021.03.003. Accessed Sept. 28, 2024. https://www.sciencedirect.com/science/article/abs/pii/S2352250X21000294?via%3Dihub.

Sewell, R. Andrew, James Poling and Mehmet Sofuoglu. “The effect of cannabis compared with alcohol on driving.” The American Journal on Addictions, Vol. 18, Issue 3 (2009): 185-93. doi:10.1080/10550490902786934. Accessed Sept. 27, 2024. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2722956/.

Shaykhet, Simon. “Michigan companies testing new tech to check cannabis use on the job.” WXYZ Detroit. Last updated Aug. 6, 2024. Accessed Sept. 27, 2024. https://www.wxyz.com/news/michigan-companies-testing-new-tech-to-check-cannabis-use-on-the-job.

Simmons, Sarah M., Jeff K. Caird, Frances Sterzer and Mark Asbridge. “The effects of cannabis and alcohol on driving performance and driver behaviour: a systematic review and meta-analysis.” Addiction (Abingdon, England), Vol. 117, Issue 7 (2022): 1843-1856. doi:10.1111/add.15770. Accessed Sept. 27, 2024. https://pubmed.ncbi.nlm.nih.gov/35083810/.

Spindle, Tory R., et al. “Assessment of cognitive and psychomotor impairment, subjective effects, and blood THC concentrations following acute administration of oral and vaporized cannabis.” Journal of Psychopharmacology, Vol. 35, Issue 7 (May 2021). doi:10.1177/026988112110215. Accessed Sept. 29, 2024. https://journals.sagepub.com/doi/10.1177/02698811211021583.

Strom, Marcus. “THC in blood and saliva are poor measures of cannabis impairment.” The University of Sydney, Australia. Dec. 2, 2021. Accessed Sept. 28, 2024. https://www.sydney.edu.au/news-opinion/news/2021/12/02/thc-blood-saliva-poor-measures-cannabis-impairment-lambert-study.html.

Sullivan, Kaitlin. “‘Arbitrary’ cutoffs of THC levels make it difficult to measure impaired driving.” NBC News. Last updated Jan. 12, 2022. Accessed Sept. 27, 2024. https://www.nbcnews.com/health/health-news/arbitrary-cutoffs-thc-levels-make-difficult-measure-impaired-driving-rcna11654.

“Understanding How Marijuana Affects Driving.” National Highway Traffic Safety Administration, U.S. Department of Transportation. Accessed Sept. 27, 2024. https://www.nhtsa.gov/drug-impaired-driving/understanding-how-marijuana-affects-driving.

“U.S. Cannabis Market Soars Amid Legal Reforms, But Safety Concerns Persist.” FinancialBuzz.com via GlobeNewswire on Morningstar. July 11, 2024. Accessed Sept. 27, 2024. https://www.morningstar.com/news/globe-newswire/9176318/us-cannabis-market-soars-amid-legal-reforms-but-safety-concerns-persist.

Vandervort-Clark, Amy. “Comparing State DUI Laws and Limits.” FindLaw. Last reviewed May 14, 2024. Accessed Sept. 27, 2024. https://www.findlaw.com/dui/laws-resources/comparing-state-dui-laws.html.

“What Does .08 BAC Really Mean to a Driver?.” Monitech. Oct. 4, 2016. Accessed Sept. 27, 2024. https://monitechnc.com/08-bac-real-meaning/.

“What’s Known and Unknown About Marijuana (Part Two).” Office of Justice Programs, U.S. Department of Justice. Jan. 31, 2024. Accessed Sept. 29, 2024. https://www.ojp.gov/news/podcast/whats-known-and-unknown-about-marijuana-part2#0-0.

White, Michael A., and Nicholas R. Burns. “How to read a paper on the short-term impairing effects of cannabis: A selective and critical review of the literature.” Drug Science, Policy and Law, Vol. 8, Issue 25 (August 2022). doi:10.1177/2050324522111904. Accessed Sept. 28, 2024. https://journals.sagepub.com/doi/10.1177/20503245221119046.

“Why .08?.” Prosecutor’s Discretion. May 24, 2013. Accessed Sept. 27, 2024. https://prosecutorsdiscretion.blogspot.com/2013/05/why-08.html.

“Why is the Nationwide Drunk Driving BAC Limit .08?.” Smart Start. Aug. 16, 2017. Accessed Sept. 27, 2024. https://www.smartstartinc.com/blog/nationwide-drunk-driving-limit/.

Wong, Kristin, Joanne E. Brady and Guohua Li. “Establishing legal limits for driving under the influence of marijuana.” Injury Epidemiology, Vol. 1, Art. 26 (2014). Accessed Sept. 28, 2024. https://injepijournal.biomedcentral.com/articles/10.1186/s40621-014-0026-z.

Wood, Edward C., and Robert L. Dupont. “Cannabis-Impaired Driving: Evidence and the Role of Toxicology Testing” in “Cannabis in Medicine” (2020): 493-513. doi:10.1007/978-3-030-45968-0_19. Accessed Sept. 28, 2024. https://link.springer.com/chapter/10.1007/978-3-030-45968-0_19.