One Beer, an Antihistamine, and an Open Container
It is 11:15 p.m. on a Saturday. Marc, 17, is the designated driver for three friends. At a party he drank one 12-ounce beer at 9:00 p.m. and took a 50-mg diphenhydramine tablet at 8:30 p.m. for allergies; the label says drowsiness may occur and to avoid alcohol. He weighs 145 pounds, has eaten dinner, and feels 'fine.' His friends are ready to leave, and one is holding an open beer in the back seat. Marc has a Louisiana intermediate license and must be home by midnight. The drive is 18 minutes on a well-lit boulevard, and he has no other way home. He has never been arrested. The nearest sober friend lives 25 minutes away. His cell phone battery is at 4 percent.
1. Assess Marc's legal risk under Louisiana's zero-tolerance law for drivers under 21.
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The legal standard is not 'feeling fine.' For a driver under 21, Louisiana's zero-tolerance law prohibits driving with a blood alcohol concentration of 0.02% or more. At 145 pounds, one 12-ounce beer can produce a low but measurable BAC depending on timing, food, and individual metabolism. Marc should not assume it has cleared just because two hours have passed.
The antihistamine makes it worse. Diphenhydramine is a sedating antihistamine, and the label warns against combining it with alcohol. The combination can increase drowsiness, slow reaction time, and impair attention even if Marc's BAC is low. The legal and safety risks compound each other.
Conclusion: Marc should not drive. If he is stopped, he risks a zero-tolerance arrest and license consequences, and the impairment from the medication makes a crash more likely regardless of the exact BAC number.
2. What about the open container and Marc's intermediate license restrictions?
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Open container: Louisiana prohibits an open alcoholic beverage container in the passenger area of a vehicle. The fact that the open beer belongs to a passenger does not make it safe or lawful. As the driver, Marc is responsible for the vehicle and should not let a friend bring an open container into the car.
Intermediate license: Marc is 17 and holds an intermediate license. That status carries restrictions, including a nighttime curfew and limits on young passengers. At 11:15 p.m., he is already inside the curfew period unless an exception applies. Driving friends home in that situation adds another violation on top of the alcohol and open-container issues.
Judgment: Even if Marc were completely sober, the open container and the curfew would be problems. He should not treat the intermediate license as a full license with no conditions.
3. What should Marc do right now, and what should he tell his friends?
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Do not drive. The safest plan is to call a sober adult, a rideshare, or the sober friend who lives 25 minutes away. Because his phone battery is nearly dead, he should ask a friend to call or use a charging cable immediately rather than waiting until the phone dies.
Deal with the open container: His friends should pour out the open beer or leave it behind before anyone gets into a vehicle. It should not be carried in the passenger area.
Do not 'wait it out' casually: Waiting might reduce alcohol effects, but diphenhydramine can continue causing drowsiness, and the intermediate-license curfew is already an issue. The practical answer is to arrange another ride, leave the car parked, and accept that he is not driving tonight. A crash or a zero-tolerance arrest would be far more costly than delaying the trip.