I Think I'm Okay to Drive: How One Beer or a Puff of Weed Can Lead to a DUI
July 9, 2023
Driving under the influence (DUI) is a serious offense that can have severe consequences for your life, your finances, and your reputation. You may think that you are safe to drive after having just one beer or smoking some weed earlier in the day, but you could be wrong. Depending on various factors, such as your body weight, metabolism, tolerance, and the type and amount of substance you consumed, you could still be impaired and over the legal limit for driving.
In this blog post, we will explain how alcohol and marijuana affect your driving ability, what the legal limits are for different substances, and what you can do to prevent getting a DUI charge.
How Alcohol Affects Your Driving Ability
Alcohol is a substance that reduces the function of the brain, impairing thinking, reasoning, and muscle coordination. All these abilities are essential to operating a vehicle safely. As alcohol levels rise in a person’s system, the negative effects on the central nervous system increase.
Alcohol is absorbed directly through the walls of the stomach and small intestine. Then it passes into the bloodstream where it accumulates until it is metabolized by the liver. A person's alcohol level is measured by the weight of the alcohol in a certain volume of blood. This is called Blood Alcohol Concentration, or BAC.
At a BAC of .08 grams of alcohol per deciliter (g/dL) of blood, crash risk increases exponentially. Because of this risk, it’s illegal in all 50 states, the District of Columbia and Puerto Rico to drive with a BAC of .08 or higher, except in Utah where the BAC limit is .05. However, even a small amount of alcohol can affect driving ability. In 2021, there were 2,266 people killed in alcohol-related crashes where a driver had a BAC of .01 to .07 g/dL .
BAC is measured with a breathalyzer, a device that measures the amount of alcohol in a driver’s breath, or by a blood test. The effects of blood alcohol concentration on driving ability vary depending on several factors, such as:
- The amount and type of alcohol consumed
- The time elapsed since drinking
- The presence of food in the stomach
- The body weight and gender of the drinker
- The use of other drugs or medications
As a general rule, one standard drink (12 ounces of beer, 5 ounces of wine, or 1.5 ounces of liquor) will raise your BAC by about .02 g/dL. However, this does not mean that you can safely drive after one drink. Depending on your individual characteristics and circumstances, you may still be impaired and over the legal limit.
For example, if you weigh 120 pounds and drink one beer on an empty stomach, your BAC could reach .04 g/dL within an hour. This could impair your ability to track moving objects, steer properly, and respond to emergency situations . If you drink another beer within the next hour, your BAC could rise to .08 g/dL or higher, putting you at risk of getting a DUI charge.
How Marijuana Affects Your Driving Ability
Marijuana is another substance that can impair your driving ability. Marijuana contains delta-9-tetrahydrocannabinol (THC), which is the main psychoactive ingredient that affects the brain. THC can alter your perception, mood, memory, attention, coordination, and reaction time.
Marijuana is usually smoked or ingested orally. When smoked, THC reaches the brain within minutes and its effects last for up to three hours. When ingested orally, THC takes longer to reach the brain but its effects last longer, up to six hours or more.
Unlike alcohol, there is no standardized way to measure THC levels in the body. THC can be detected in blood, urine, saliva, or hair samples, but these tests do not necessarily indicate how much THC is in the brain or how impaired a person is. Different states have different laws regarding marijuana use and driving. Some states have zero-tolerance laws that prohibit any detectable amount of THC in the blood or saliva of drivers. Other states have per se laws that set a specific limit for THC concentration in the blood (usually 5 nanograms per milliliter). Some states do not have any specific laws for marijuana impairment and rely on the officer's observation and judgment.
Regardless of the legal status of marijuana in your state, driving after using marijuana is risky and can lead to a DUI charge. According to a meta-analysis of 21 studies published in 2012 , drivers who test positive for marijuana are more than twice as likely to be involved in a crash than drivers who test negative. The risk increases with higher doses of THC and with the combined use of alcohol and marijuana.
How to Avoid Getting a DUI Charge
The best way to avoid getting a DUI charge is to never drive after consuming alcohol or marijuana. Even if you think you are fine to drive, you may be wrong. You may not realize how impaired you are or how much substance is in your system. You may also encounter a sobriety checkpoint or a random traffic stop that could expose your impairment.
Here are some tips to help you prevent getting a DUI charge:
Plan ahead. If you know you are going to drink or use marijuana, arrange for a sober ride home. You can use a rideshare service, a taxi, a designated driver, or public transportation. You can also stay overnight at a friend's place or a hotel.
Know your limits. If you do drink or use marijuana, be aware of how much and how often you consume. Keep track of your drinks and avoid mixing different types of alcohol or drugs. Eat food and drink water to slow down the absorption of alcohol or THC.
Wait it out. If you do end up driving after drinking or using marijuana, make sure you wait long enough for the substance to wear off before getting behind the wheel. The only way to lower your BAC or THC level is by time. No amount of coffee, water, food, or exercise will speed up the process. As a rule of thumb, it takes about one hour for your body to eliminate one standard drink of alcohol. For marijuana, it may take several hours or even days for THC to clear from your system, depending on how much and how often you use.
Be respectful and cooperative. If you do get pulled over by the police, be polite and follow their instructions. Do not lie, argue, or resist. Provide your license, registration, and insurance information when asked. You have the right to remain silent and to refuse field sobriety tests or preliminary breath tests. However, if you are arrested for DUI, you may be required to submit to a chemical test (blood, breath, or urine) under the implied consent law. Refusing this test could result in harsher penalties, such as license suspension or revocation.
Driving under the influence of alcohol or marijuana is dangerous and illegal. It can impair your driving ability and increase your risk of getting into a crash or getting a DUI charge. You may think that you are safe to drive after having just one beer or smoking some weed earlier in the day, but you could be wrong.
The best way to avoid getting a DUI charge is to never drive after consuming alcohol or marijuana. If you do drink or use marijuana, plan ahead for a sober ride home, know your limits, wait it out, and be respectful and cooperative if you get pulled over.
Remember, buzzed driving is drunk driving, and high driving is impaired driving. Don't take the chance and put yourself and others in danger.