More and more, people are finding out the hard way that DWI does not just mean alcohol. Marijuana smokers can also get a DWI just as easily these days. Police officers are more on the lookout for driving under the influence of marijuana. In the past police would be more geared to make an arrest for possession of marijuana. These days, a driver might get arrested for DWI and think the penalties are different and distinct from the more still much more common alcohol-related DWI. They are not. The penalties for an alcohol-related DWI and a marijuana-related DWI are the same. As discussed below, intoxication for these two substances are very different. There are many problems with prosecuting a marijuana DWI that are different. This article discusses the unique and distinctive qualities of a DWI involving marijuana or THC.

Marijuana DWI

Marijuana Affects The Body Differently Than Alcohol

The statute, Texas Penal Code Section 49.01 defines intoxication as alcohol, controlled substance, drug, or dangerous drug. Compared to marijuana and other drugs, establishing intoxication by alcohol is much easier for a couple of reasons. The ways that the human body absorbs and eliminates alcohol (ethanol) is widely studied and understood. Alcohol is one of the most studied molecules in the world, and alcohol behaves very predictably across a wide spectrum of people. Studies have shown that people display impaired motor function, slowed response time, and impaired judgement regardless of tolerance. Tolerance is a very important factor in establishing marijuana intoxication.  

Law enforcement and prosecution tools were tailored to prosecute people for DWI who have been intoxicated through ingesting alcohol, not marijuana. The field sobriety tests were studied, tested, and designed for alcohol. These tests are used to detect marijuana, but they don’t fit. This is a bit like playing basketball with a soccer ball. They were not designed for marijuana. They were validated decades ago when DWI with marijuana was not something that was on the radar of law enforcement across the country.  

Marijuana Intoxication is Unique   

As noted above, how someone responds physiologically to marijuana can be a major factor. Marijuana intoxication is very elusive and difficult to pin down. It always depends on context. A forensic analyst cannot simply look to a number above .08 BAC (as they will in an alcohol case) and say that a person is intoxicated. And a prosecutor cannot shake a piece of paper around with a number on it (such as a number .08) in front of a jury and base their entire prosecution on that number. It is more complex than that, and each case is different. Marijuana can be detected in the blood and measured using mass spectrometry, yet these levels do not matter without context. Without knowing how a person is affected, it does not matter how high or low a person’s THC concentration is. This is because a person’s tolerance to marijuana is a major factor. If someone is a habitual marijuana smoker and smokes marijuana daily, they will have very elevated levels of THC in their blood, even if they are not high. During a jury trial, the state must prove intoxication beyond a reasonable doubt. The way in which they try to do this is to have an analyst testify as an expert witness that the person was intoxicated at the time of driving. However, the analyst must admit that they really have no idea based on the levels alone. Even a chronic smoker can have levels greater than 100 nanograms in their blood and not be under the influence. An analyst with knowledge of how marijuana interacts in the human body will admit that unless they lack expertise or they are lying.           

What is the Law in Texas?

The DWI laws in Texas are in Chapter 49 of the Texas penal code. DWI consists of four elements which a prosecutor must prove beyond a reasonable doubt. These elements are: operating a motor vehicle in a public place while intoxicated. As noted above, intoxication can be from alcohol, drugs, dangerous drugs, or any combination. The same DWI laws apply to marijuana-related cases as alcohol-related cases. DWI can be either a misdemeanor or a felony. Generally, DWI is a misdemeanor. One difference is that a person’s first DWI will always be a Class B misdemeanor if only marijuana is involved. For alcohol, it can be a class A misdemeanor if the blood alcohol concentration is above .15 grams per deciliter, which is almost twice the legal limit. For marijuana, there is no legal limit so it is always a class B. If a person has a prior conviction for DWI, the second DWI will be a class A because it will be enhanced. Class B misdemeanors have a potential punishment of between 3 and 180 days in jail and a maximum fine of $2,000. Class A misdemeanors raise the maximum jail time of up to one year and the maximum fine up to $4,000.

What About Felony DWI?    

A DWI involving marijuana can also be a felony. There are several ways to get a felony DWI. The most common is repetition. If a person has two prior convictions for DWI in Texas or in another state, the state of Texas can enhance the charge to a felony. This is called felony repetition DWI or third DWI, and it is a third-degree felony. Another way to get a felony DWI is getting arrested with a child under 15 years old in the car. The most serious way to get a felony DWI is if someone else endures either serious bodily injury or death. This could be a passenger in the same vehicle or it could be someone in another vehicle or a pedestrian. If someone suffers serious bodily injury, the charge will be intoxication assault. If someone dies, it will be intoxication manslaughter.       

How Much Marijuana Does It Take to Get a DWI?

Marijuana is tested in a person’s blood using a machine called the gas chromatograph and mass spectrometer. It is measured in nanograms, and readings will be anywhere from two nanograms to over one hundred. There is no set limit in Texas, so any amount of a blood test generally over 3 nanograms will get filed. Different states have different marijuana limits. Some states have specified per se limits. like Texas has with alcohol. The legal limit for a person’s blood alcohol concentration is .08 grams per deciliter, and that is the law in every state except for Utah, which recently changed the law to .05 grams per deciliter. Depending on a person’s body size, it only takes a few drinks to get to .08 BAC. States that have legalized marijuana have per se limits like Colorado’s legal limit of 5 nanograms per milliliter. This is an arbitrary amount because unlike alcohol, the numbers do not matter. In Texas there is no limit, and prosecutors are restricted to proving a loss of normal physical or mental faculties. Although, forensic analysts will testify that 5 nanograms is an intoxicating amount. This is arbitrary at best, and a skilled DWI defense lawyer will be able to raise all kinds of doubt. Even if the number is greater than 100 nanograms, it is difficult to say with any kind of confidence if someone is intoxicated. This is especially true for chronic smokers.     

How Does Marijuana Affect Drivers?

The answer to this question is complex and cannot be easily answered. Marijuana affects everyone differently, and few assumptions can be made about correlating any amount of alcohol and performance in driving or performance in any function requiring mental or physical abilities. This is good news for people charged with driving while intoxicated cases involving marijuana or THC. Some studies have shown driving becomes safer with marijuana, because people who are under the influence of marijuana can be highly conscious of being high on marijuana. They often alter their behavior and slow down their driving. There is no way to say in general how marijuana impacts driving. There are so many studies that discuss how alcohol negatively impacts reaction time and the ability of drivers to operate a car. Study after study over decades detail how drinking alcohol in elevated amounts can worsen a driver’s ability to follow the rules of the road and make roads less safe. As mentioned before, everyone reacts differently to marijuana and this can make prosecuting a DWI involving marijuana difficult for prosecutors who don’t understand the science behind marijuana and how it metabolizes and impacts the body and mind. There are hurdles in explaining science to a jury and helping them overcome their biases to marijuana, because many people still do harbor biases and make judgements about people who smoke marijuana. Even if they don’t have biases, many people do not understand marijuana that well if they don’t have personal experience using it.     

What are the Different Kinds of Marijuana and THC?

The number of variations of marijuana and THC products has exploded in recent years. This has coincided with the legalization in many states across the country, and the number of states legalizing marijuana continues to grow. (There are huge differences in penalties between marijuana and THC—marijuana in amounts under four ounces is still a misdemeanor, while any amount of non-marijuana THC is a felony. For more discussion on this click here: Possession of THC). However, the analytical tests used to detect marijuana is called gas chromatography and mass spectrometry do not distinguish between marijuana and other compounds that contain concentrated THC. It only detects THC itself, which is the psychoactive compound in marijuana that gets people high. You cannot possess something that is already metabolizing in your body, and you cannot be prosecuted for possession. This means if you are already high and get arrested for DWI, law enforcement cannot distinguish if you smoked marijuana or ingested edibles or dabbed or used a THC vape. It is all penalized in the same way depending on the level of DWI charge. So in light of that, here are some kinds of THC concentrates that, if detected in a blood test, can lead to a DWI case filed:

THC Extracts

The amount and variety of THC extracts has increased substantially in the last several years and continues to increase in kind and potency. Legal THC is a booming business in many states and this has created a market for business to innovate and develop new and different products. These new products show up in all states, even in those that have not taken legislative steps to legalize marijuana or THC. This discussion is not about the penalties of possessing these substances, but to detail some of the kinds of marijuana and THC products that if smoked or ingested can lead to a DWI charge and arrest. 


This is a soft texture substance that is very potent. Crumble easily breaks apart like a soft cookie and it can be smoked, dabbed, or it can be utilized in a vapor device.


This is also soft like crumble but oilier, stickier in its consistency. It has a texture that is close in nature to butter, which is how marijuana enthusiasts named it budder (very creative, right?). It is oil based and fatty in nature, like butter, and can be smoked or dabbed or vaporized.


This is the accumulation of the very fine and very sticky crystalline components of the flower of the marijuana leaf. These fine parts of the flower are called trichomes. They are glands consistency of resin and they are characterized by their potency and very high content of THC


This THC concentration appears in clear translucent glass-like sheets. Shatter usually appears as the color of amber and looks like distilled and unclouded amber tree sap. Alternatively, shatter can be stretchy and pulled apart like taffy. Shatter can be smoked or vaporized.


Wax is the opposite of shatter in clarity of appearance. It is also denser molecularly than shatter is. Wax is cloudy and opaque in appearance. It is soft in texture and can appear lumpy and formless and look like a glob of lip balm.       

What are Some Defenses?

Marijuana and THC DWI charges can result from marijuana alone, or marijuana and alcohol, or marijuana and other controlled or prescribed substances. This section is about marijuana by itself. The key defense to a marijuana DWI allegation that only involves marijuana and not alcohol is that a person was not high at the time of driving. This sounds simple, but it might not be. This argument can be made if certain circumstances are present. Of course, it depends on the facts, but the video of the person performing the field sobriety tests must be good or reasonably good for this to be effective. It is best if the person does not make any statements about just having smoked. It is best if there is not marijuana smoke in the vehicle and any blunts or joints in the ashtray. However, you can have a defense even if these factors are present. The thing about marijuana DWI, as discussed above, is that marijuana affects people differently. Intoxication, and what intoxicated means depends on the person and their experience with using marijuana or THC. There are two kinds of THC that the mass spectrometer will detect. There is THC, which is the psychoactive compound. That is what makes people high. Then there is THC COOH, which is the inactive compound that is not psychoactive. This does not make people high, and only measures whether or not a person has a history of smoking or ingesting THC. If a person is a chronic smoker, they will have a high THC COOH. Even if THC is detected, if the person is a chronic smoker and has a high THC COOH, they are not necessarily high or intoxicated at the time of driving. This is because active THC can linger in habitual users. This can be an effective defense in any marijuana DWI case.    

What about Tolerance?   

Tolerance has been discussed in this article and can be a huge factor in defending a DWI charge with THC. Tolerance develops when a person habitually smokes marijuana. Some people use marijuana occasionally, and some people uses marijuana daily. Some people smoke or ingest THC in another way on a daily basis. When someone uses marijuana every day, and especially if they smoke it multiple times a day, a legitimate argument can be made that they are more normal when they do use it. Marijuana is unlike alcohol, which intoxicates people along fairly predictable lines. If it can be shown that a marijuana smoker has a high tolerance to THC, it becomes very difficult to establish intoxication using a chemical test. It must be shown using other facts, like the person’s performance on the field sobriety tests. How they are driving, what they say are also factors. The differences in alcohol and marijuana are discussed in greater detail above. It is well known in the scientific community that factors such as quantity of alcohol and other factors such as temporal factors that reveal how alcohol is absorbed and eliminated in the human body, can go a long way to determining intoxication. This is why there is a per se limit of intoxication with alcohol. This is .08 grams per deciliter. As discussed more below, there is no per se limit in Texas. Per se limits are very difficult. States that penalize 2 or 5 nanograms of THC in the blood end up convicting people who are not guilty of DWI. This is just a fact. Ultimately it is up to defense attorneys to learn the skills and the science and learn how to explain the science to juries so that this does not happen.      

Habitual Smokers are Different

If someone habitually smokes or uses edibles, and the mass spectrometer shows that the person has a very high reading of the inactive THC molecule (THC COOH), then they can have a corresponding active THC reading without being intoxicated. The importance of this cannot be overstated to any criminal defense. In some cases, this can be the entire defense. If someone is not intoxicated at the time of driving, then the defense lawyer has a great defense. Generally, the state of Texas will not dismiss these cases even in light of this argument and the science that backs it. The defense lawyer will have to convince a jury to prevail.  

Loss of Physical or Mental Faculties

A very important aspect of any DWI prosecution is the loss of the normal use of physical and mental faculties. This is the legal definition of intoxication in Texas. There are three ways intoxication is defined: loss of physical faculties, loss of normal mental faculties, and having an blood alcohol concentration of .08 grams per deciliter. Since this number is not relevant to a marijuana or THC only DWI, the only way for the state to get a guilty verdict is by showing loss of normal physical or normal mental faculties. How can this be shown? The state will first look to show bad driving that indicates intoxication. There are 24 cues in the NHTSA manual that police are looking for. These cues include things like swerving and drifting across lanes, driving without headlights at night, and driving over curbs. They will also look to what a person says to police, and if their words are slurred and if their eyes are red, bloodshot, or watery. The most important piece of evidence regarding mental and physical faculties are the field sobriety tests. The standardized field sobriety test battery consists of three tests: the horizontal gaze nystagmus test, the walk and turn test, and the one leg stand. There are many ways for a skilled DWI defense lawyer to attack these tests. For a longer discussion of how to attack the reliability of these tests, click here.   

There Are Not Per Se Marijuana Levels in Texas

In many states, especially the states that have legalized recreational marijuana, per se limits have been established as a threshold for intoxication. Per se means that if a person has a test that shows .02 and .05 nanograms, then this is enough for a prosecutor to tell a jury that this person is intoxicated. In Texas, there is no per se limit and there is no amount that legally means a person is intoxicated. Prosecutors will always show the jury whatever the amount is if it appears in the blood, and they will have the analyst testify that a person would be intoxicated (the analyst must always testify in any DWI case that involves a breath test or blood test). If you have been arrested for any DWI, or any DWI involving marijuana in Texas, call me to discuss your case and your options.