Impaired Driving

Why is this important?

You've probably heard someone say "Don't drive if you've had too much to drink!". Seems like a pretty good thing to say, right? Well, if you think about it a bit more, that common warning really doesn't make sense. Why? People have a really hard time judging their own level of intoxication. Ironically, intoxicated people are the worst judge of how impaired they really are, because the alcohol (or another substance) is impairing their judgment!

A lot of things can cloud your judgment of your own impairment or exacerbate your level of impairment, even if you are at or below the "legal limit" to drive (when it comes to alcohol). For instance, if it's really late at night and you're tired, or if you haven't eaten, or if you've consumed a caffeinated energy drink—all of these things can mask or compound your true level of impairment. So, our best advice is to avoid any level of drinking and driving. Period.

Car dashboard from the perspective of the driver. Outside the car it is dimly lit, and it is raining, making it difficult to see.

While alcohol certainly remains an ongoing concern (1) when it comes to young adult driving, cannabis-impaired driving is emerging as an additional concern and can be even murkier than alcohol when it comes to knowing when it is "safe" to get behind the wheel.

In fact, there is no current scientifically agreed-upon limit that can be reliably used when it comes to how long to wait after cannabis use before it is safe to drive. In fact, if you search for this information, you will see very different recommendations, often ranging between 4 to 12 hours after a person's last use (or longer!). Why is this? Well, cannabis products are highly variable in both the level of THC contained within them and how they are processed by the body. A THC-containing edible, for example, is metabolized over many hours and its effects might be different compared with the effects of smoking or vaping a cannabis product (2). So just like alcohol, the best advice is to not drive after using cannabis. Even if someone feels like the effects have worn off and they are safe to get behind the wheel, they are likely still impaired, and research has demonstrated this to be the case. For example, in a study of regular cannabis users, nearly half (48%) said they felt safe to get behind the wheel only thirty minutes after smoking, and more than two thirds said they would drive just ninety minutes after smoking, even when their driving abilities were clearly impaired on the simulator used (3). Simply put, the science is clear that people cannot trust how they are feeling as a barometer for when they can get behind the wheel.

So how can you convey these messages to your college student?

It's important to have these conversations because college students are at high risk for impaired driving and car crashes for two main reasons. First, they have relatively little driving experience (and they can become easily distracted by other passengers), and second, they tend to engage in a lot of risky activities related to drinking (4, 5). National statistics show that 29% of college students between the ages of 18 and 24 drove under the influence of alcohol, and of the 8 million U.S. college students, 3 million rode with a drinking driver during the past year (6). When it comes to cannabis, national statistics show that of those students who both drove and used cannabis during the past 30 days, 30% reported driving within 6 hours of cannabis use (7). This is a much higher percentage of students compared with students who report drinking and driving. Of student drivers who reported drinking during the past 30 days, 13% reported driving after any amount of alcohol. While anything above zero is too much, it is particularly concerning that students do not appear to perceive cannabis to be as risky when it comes to driving.

NOT driving after consuming any amount of alcohol or cannabis—and NOT being the passenger in a car with a driver who has drank and/or used cannabis—are important messages for college students (8). The basic message is that whenever you get into a car, make sure the person behind the wheel has NOT been using substances—especially if it's you! If your student alludes to driving at all when they go out, this is the time to flex your muscles as an adult family member. Impaired driving is a serious issue with life-threatening consequences, and you shouldn't be hesitant to emphasize it.

Having conversations about impaired driving with your student will not only be relevant to their college experience, but also help them learn how to be a safe driver for life.

Say This:

'When you go out with your friends, how do you usually get home?"

Conversations about impaired driving can happen any time. One way to start this conversation is to ask about how your student gets home when they go out.

"I'm glad you don't get in a car with someone who has been drinking."

"I really hope you aren't driving after you drink or riding with someone who has been drinking. This is a serious matter, and I expect you never to do it."

"Driving after drinking is totally preventable. There is absolutely no good reason ever to drink and drive. There are many alternative options."

If they say walking or taking the bus, then you should encourage that and tell them it makes you proud that they don't drive under the influence or ride with someone who has been using substances. However, taking the bus or having a sober (not just less intoxicated) designated driver is better than walking for safety reasons, if possible.

"Do you ever worry about your friends driving after drinking? How have you or would you talk to them about your concern?"

"Have you ever worried about being in a car where the driver has been using substances even if you haven't been drinking? How do you manage that situation?"

A conversation about friends can be a useful icebreaker.

"Getting a DUI is no joke. DUIs can create a multitude of legal problems that cost thousands of dollars, make insurance rates go up, and can ruin future employment opportunities."

"I don't want you to drive after using any substance. Remember, any amount can impair one's driving capabilities. Even if you only feel a little different, you should not operate a vehicle."

In the state of Maryland people younger than 21 may not drive a motor vehicle with a blood alcohol concentration above .02 (8). For many people, that would translate into one or two drinks!

Ever overhear your student bragging about how much they can drink? Students who they think they can handle 4 or 5 drinks without getting drunk are at especially high risk for drunk driving (9).

While state laws vary (10), many do not allow for any amount of cannabis use for those who get behind the wheel, and if the officer suspects impairment, you can still get a DUI, just like with alcohol.

"Does your campus have a "Safe Ride" program? You should keep that number in your phone just in case."

Many campuses have "Safe Ride" programs for students who have consumed alcohol. Encourage your student to keep the number for this program handy, or in their phone.

"Public transportation is a great way to get from point A to B."

Talk to your student about taking buses and subways if they plan to drink or use cannabis. Let your student know that it is okay to pay for a taxi. While many students feel strapped for money, spending a few dollars on a safe ride home is worth it.

"Mixing caffeinated energy drinks with alcohol is never a good idea. You won't realize how impaired you really are."

Mixing energy drinks with alcohol can be particularly dangerous because it can mask feeling drunk (11).

"I'm worried that you are getting in a car when you (or your friend) are under the influence. Your safety is important to me and I think we should talk about this."

If you think or know that your student is driving while under the influence, it is very important that you address the issue with them before they or someone else causes serious harm.

"I expect you to never get behind the wheel or be a passenger when you or the driver has been using any substances."

"Driving under the influence is a serious thing. Please think about your safety, your friend's safety, and the safety of others."

"You are gambling with your life when you drink and drive."

Be straightforward with your student and discuss negative consequences.

If your student still won't listen to you, you have the option to take away their car or stop paying for their car insurance, so that they can't drive at all.

"A lot of people have the misperception that cannabis is not as impairing as alcohol and therefore it is okay to drive after using. I need you to understand this is not the case."

"Even if someone tells you they are safe to drive, that they "only smoked a little bit", I want you to not get in that vehicle. It's better to be late or pay for a rideshare than to get hurt or get into legal trouble."

"Let's roleplay what you could say in that type of situation. If someone insists that they are fine to drive, how could you respond?"

Make sure your student understands that just because there is a belief out there that cannabis does not really impair driving ability, it doesn't make it true.

Brainstorm with them how to handle social situations where they experience peer pressure that can override what they know to be the right thing to do. Thinking through these types of situations ahead of time will make it easier for them to make the right choice in the moment.

Not This:

"In an emergency, it is okay to drive under the influence."

Don't condone impaired driving in any situation.

If you say, "In an emergency, it is okay to drive even if you're feeling impaired", your student will not realize the real danger associated with substance-impaired driving.

"It's okay to drive if you have only had a few drinks."

If you say "It's okay to drive if you have only had a few drinks," your student might be putting themselves and others at risk by getting behind the wheel when they are impaired and not even realize it. There is no standard to say how many or how few drinks will impair a driver's ability, and any consumption before driving should be discouraged.

If you know your student is drinking and driving, it is understandable to feel angry or upset. However, don't yell at your student as they will not be receptive and might shut you out completely. It is important to help them. Having the ability to communicate effectively is an important step towards that goal.

Don't just discourage drinking and driving because it is illegal. That suggests that your student's safety isn't a concern. Emphasize both safety and legal consequences.

Impaired Driving References

Scientific References

Lange J. College students are still driving impaired and we need to do something about it. U.S. Drug Enforcement Agency. Accessed November 22, 2024. http://www.campusdrugprevention.gov/views-from-the-field/college-students-are-still-driving-impaired
Zhao S, Brands B, Kaduri P, Wickens C, Hasan O, Chen S, Le Foll B, Di Ciano P. The effect of cannabis edibles on driving and blood THC. J Cannabis Res. 2024;6(1):26. doi:10.1186/s42238-024-00234-y
Marcotte T, Umlauf A, Grelotti D, Sones E, Sobolesky P, Smith B, Hoffman M, Hubbard J, Severson J, Huestis M, Grant I, Fitzgerald R. Driving performance and cannabis users' perception of safety: A randomized clinical trial. JAMA Psychiatry. 2022;79(3):201-209. doi:10.1001/jamapsychiatry.2021.4037
Hingson RW, Heeren T, Zakocs RC, Kopstein A, Wechsler H. Magnitude of alcohol-related mortality and morbidity among U.S. college students ages 18-24. J Stud Alcohol. 2002;63(2):136-144. doi:10.1146/annurev.publhealth.26.021304.144652
Wechsler H, Lee JE, Kuo M, Seibring M, Nelson TF, Lee H. Trends in college binge drinking during a period of increased prevention efforts: Findings from four Harvard School of Public Health College Alcohol Study surveys: 1993-2001. J Am Coll Health. 2002;50(5):203-217. doi:10.1080/07448480209595713
Hingson RW, Zha W, Weitzman ER. Magnitude of and trends in alcohol-related mortality and morbidity among U.S. college students ages 18-24, 1998-2005. J Stud Alcohol Drugs Suppl. 2009;16:12-20. doi:10.15288/jsads.2009.s16.12
American College Health Association. American College Health Association-National College Health Assessment III: Reference group executive summary spring 2024. 2024. https://www.acha.org/wp-content/uploads/NCHA-IIIb_SPRING_2024_REFERENCE_GROUP_EXECUTIVE_SUMMARY.pdf
Code of Maryland Regulations 11.17.15.02
Arria AM, Bugbee BA, Caldeira KM, Vincent KB, O'Grady KE. Subjective drunkenness: Relation to drunk driving risk and possible utility as a novel screening item for alcohol-related consequences among college students. presented at: Am Public Health Assoc; October 31-November 4 2015; Chicago, IL.
Governors Highway Safety Association. Drug-impaired driving laws. Governors Highway Safety Association. Accessed November 22, 2024. https://www.ghsa.org/state-laws/issues/drug%20impaired%20driving
Arria AM, Caldeira KM, Kasperski SJ, Vincent KB, Griffiths RR, O'Grady KE. Energy drink consumption and increased risk for alcohol dependence. Alcohol Clin Exp Res. 2011;35(2):365-375. doi:10.1111/j.1530-0277.2010.01352.x

Disclaimer: Unfortunately, even with the "best" parenting practices, there is no guarantee that students will refrain from starting to use drugs or alcohol, developing a drug problem, or even worse, experiencing serious drug-related consequences. Conversely, the worst of circumstances does not necessarily predispose one to a life of addiction.