Firm Announcements and Law Updates

Driving While High In Colorado & California

While law enforcement claim the legalization of marijuana has led to (1) a rise in crime, (2) increased vehicle accidents, (3) and increase in youth addiction to marijuana they are generally wrong (Heuberger, 2017; Ingould, 2016; Morris et al. 2014; Reuters, 2017; Smith, 2017).  It is true Colorado has seen a small rise in crime but it is primarily connected to increasing income inequality and increased alcohol consumption (e.g. violence tends to go up when economies are booming but a large group of people do not experience the benefits like what we are experiencing here in Denver and Colorado at large and in Southern California). 

Nevertheless, law enforcement has stepped up its efforts to arrest and prosecute people that are driving while high.  However, there are serious problems with how the state investigates and detects marijuana in someone’s system.  You need a lawyer who understands these issues and knows how to present them in court.

1st Issue:  Unconstitutional Searches

Only a blood, saliva, hair or urine test can detect marijuana, or more specifically THC, in your system.  In Colorado and California law enforcement only uses a blood test to detect THC in your system - a breath test does not yet exist.  More often than not, law enforcement will attempt to say the drivers they encounter have likely been drinking and the initial arrests are related to alcohol rather than marijuana.  The reality here is that most police officers are trying to make arrests for alcohol with the hope of detecting THC later on because it is difficult, if not impossible, to simply talk with someone you’ve never met and know they have recently smoked marijuana unless you can smell it on them.  It is even more difficult if the marijuana was consumed through food or liquid. 

First, after being arrested for a possible alcohol related DUI police officers are directly asking people to take blood tests and not giving them the chance to take a breath test.  Under the Colorado Express Consent statute police officers must give you a choice between a breath or blood test – they can only force you to take a particular test if ‘exigent circumstances’ exist.  Exigent circumstances are things like you’re un-conscience because of a car accident or the police officer’s breathalyzer at the station is not working – and these reasons have to be communicated to you and in the police report.  Thus officers telling you to take a blood test only are violating the law.

Second, most law enforcement officers will write reports indicating their arrest was based on alcohol and when you submit to a blood test they will have the crime lab do a search for THC in your system.  This is unconstitutional – police officers must have probable cause (e.g. articuable facts) to search for THC – they simply cannot search for anything.  Police officers are trying to claim in court that the effects of alcohol and marijuana on a person are virtually identical and thus an arrest for a traditional DUI/DWAI gives them probable cause to search for marijuana.  We know this is not true but unfortunately most lawyers simply do not realize police officers rarely know if the people they arrested have actually ingested marijuana. 

Nevertheless, most lawyers will have their clients plea to a driving while high charge anyway because they don’t know how, or are afraid, to go after a police officer in court.  In a recent case (CR17-545) I got the THC evidence thrown out of evidence as an unconstitutional search under the 4th amendment because the officer ordered a blood test to search for alcohol and THC but at no point did the officer state in his report anything that would indicate he believed my client had consumed marijuana.  On the stand, that officer was more than happy to editorialize his report and claim the effects of marijuana and alcohol are the same without any evidence (training, science, etc...) to back that claim up.  In the end, the judge ruled in my favor and made sure to apologize to the prosecutor. 

2nd Issue:  Absorption and Detection of THC

The dirty little secret right now is that crime labs are not very good at actually determining how much THC you have in your system at any given time.  Colorado has stated that you can be charged with driving while high if you have 5 ng/ml or more in your system.  However, all people absorb THC differently, may even have constant rates of THC in their system, and crime labs may be able to detect the element of THC but have to engage in mathematical gymnastics in order to actually determine how many ng/ml is in your system.

When it comes to absorption there is a difference between casual users and chronic users of marijuana.  It also matters how you ingest marijuana (e.g. smoke, solid food, liquid form).  First, scientists have not come to an agreement as to what defines a ‘casual’ and ‘chronic’ user of marijuana – hence it is no surprise that every study done on absorbing THC into our systems has produced a large variety of results.  Furthermore, the studies done often times include only a handful of study participants (e.g. 25 people, 6 people, 9 people, etc...) which in no way allows scientists to make generalizations about THC absorption and the population at large.  Moreover, the times people ingest marijuana varies between individuals (e.g. 1 hour, 2 hours, 30 min., etc...) which means there will be a ton of variance in THC levels in each individual because of the time differences between consumption.  Therefore, there is just no way right now for any scientist to claim we know to any degree of certainty that there is a general rate of THC absorption in the population.  I have seen crime lab representatives openly lie about this issue in court and claim that they can make such generalizations about absorption rates but when cross-examined about the scientific methods allowing them to make such a generalization they cannot actually say what it is. 

This matters because the known ‘absorption rates’ for the general population is how crime-labs calibrate their machines to detect marijuana.  Like with blood tests for ethanol (see my older blog post from 1/10/2018), the level of THC in your system is determined through a regression analysis.  Unfortunately, crime labs will not release any information regarding how they construct the data base they run regression analyses off of which means we cannot validate whether or not the statistical models used are appropriate.  Nevertheless, because we as people absorb THC at varying rates the presumption has to be the statistical models used by crime-labs to measure THC in our blood is likely inaccurate.  Crime labs can rebut this presumption if they begin to behave like ethical researchers and make their data and methods public. 

Another issue has to do with people that consume marijuana on a regular basis.  There is actually a good chance that after years or months of continued use, an individual may constantly have 5 ng/ml of THC in their system even if they have not recently consumed marijuana.  Law enforcement simply has no way to know if the THC in your system is ‘constant’ or due to recent consumption of marijuana smoking.  You must remember that THC attaches to fatty cells and thus stays in our system for long periods of time (up to 45 days) hence the more you consume marijuana the more THC you’ll have in your system even if the effects have worn off. 

A final issue has to do with the statistical methods used to quantify THC in your system.  Crime labs will not release the data they use so we can re-construct the linear regression models used in their analysis – hence they are hiding something.  In a recent study, House et al. (2017) found measurements for THC in whole blood over a six day period, using 16 samples, they found the accuracies of detecting and quantifying ng/ml in the blood produced accuracies from 0.52% to 8.63% and that when looking at the same sample multiple times there was variation in detection and quantification that ranged from 1.91% to 7.69%.  The whole point of their study was to find a method better than what we are currently using to detect and quantify THC – unfortunately for law enforcement they demonstrated that detection and quantification of THC in the blood is still questionable. 



Brooke, Arterberry; Hayley Treloar and Sarah Pedersen (2013).  Marijuana Use, Driving and Related Cognitions.Psychology of Addictive Behaviors.  27(3): 8554-860. 

House J., C. Lyttle and C. Blanchard (2017).  An Ultra-High-Pressure liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the detection of cannabinoids in whole blood using solid phase extraction.  Canadian Society of Forensic Science Journal.  50(3): 103-113. 

Ingold, John (2016).  Marijuana Use Remains Flat Among Colorado Teens Survey Finds.  The Denver Post.

Morris, Roberg, Michael TenEyck, J.C. Barnes and Tomislav Kovandzic (2014).  The Effect of Medical Marijuana Laws on Crime:  Evidence from State Panel Data, 1990-2006.  PLoS ONE, 9(3): e92816.

Neavyn, Mark; Eike Blohm; Kavita Babu and Steven Bird (2014).  Medical Marijuana and Driving:  A Review.  Journal of Medical Toxicology.  10(1): 269-279.

Reuters News (2017).  Colorado’s Teen Marijuana Usage Dips After Legalization:  Government study puts the state’s high school cannabis use below the national average.

Smith, Chuck (2017).  Marijuana Legalization has not Increased Traffic Fatalities.  Colorado Politics.