Unfortunately, drunk driving remains one of the most common causes of injury and death while driving in the United States. Drunk drivers have slowed reaction times, distorted senses, and are likely to underestimate their own impairment, insisting on driving when they’re clearly unable to do so. But at the same time, if you’ve only had one drink, and it’s been a few hours since then, you should be clear to drive normally.
So what actually counts as “drunk driving,” and how can you be sure you’re okay to drive safely?
The Legal Definition of a DUI
Different states have minor variations in how they treat driving while intoxicated, using acronyms like driving under the influence (DUI), driving while impaired (DWI), or operating while intoxicated (OWI). However, in the United States, you can generally count on being over the legal limit if your blood alcohol concentration (BAC) is 0.05 or more. This metric calculates what percentage of your bloodstream is alcohol, and is useful for determining how “drunk” a person is. Of course, while this is valuable for legal purposes, just being under the legal limit isn’t a guarantee that you’re completely safe to drive.
When you drink alcohol, alcohol will gradually filter into your bloodstream, where it begins to affect your body. Over time, it metabolizes, reducing its effects, which is why it takes a while to “feel” drunk after drinking, and you can continue to feel drunk well after you consume your last beverage.
Of course, the rate at which alcohol enters your bloodstream, the total volume of your bloodstream, and the rate at which alcohol is metabolized is going to vary from person to person. A short, light woman with a slow metabolism could be over the legal limit after a couple of beverages and a couple of hours, while a tall, heavy man with a fast metabolism could drink more and be completely fine.
One standard drink of alcohol is considered to be about 12 ounces of beer, 8 ounces of malt liquor, 5 ounces of wine, or 1.5 ounces of distilled spirits. As a general rule, you’ll need to allow at least an hour to pass after every standard drink you consume before you can safely drive. Some people will need to wait even longer.
Factors That Influence Intoxication
So what factors can influence how intoxicated you are after consuming alcoholic beverages, as well as your capacity to drive?
- Gender. Men and women process alcohol at different rates. Accordingly, women generally have to wait longer for the effects of alcohol to subside, though this is only one of several factors to consider.
- Weight. Heavier people tend to feel the effects of alcohol less. The more body weight you have, the more space alcohol has to diffuse. The lighter you are, the faster alcohol will make you feel intoxicated, and the more drunk you’ll feel overall. The heavier you are, the longer it will take to feel drunk, and the less drunk you’ll feel for the same amount of drinks.
- Metabolism. Different people have different metabolic rates, usually attributable to genetic differences. Two people of the same weight and gender could have very different metabolic rates, with one processing a standard drink of alcohol in 45 minutes and another taking 75 minutes. Some bodies are simply better at converting alcohol and reducing its concentration in the bloodstream. Unfortunately, it’s hard to directly measure this impact. Most people just end up with an innate sense of whether they’re close to the average, or whether they’re an outlier in one direction or the other.
- Personal tolerance. Alcohol is a drug, and like any drug, the more you use it, the more your body becomes acclimated to it. Over time, and the more you drink, the more tolerant you’ll be of the drug, and the more it will take to get you drunk. People who drink heavily and often can therefore consume more drinks before they’re considered too intoxicated to drive.
- Time. No matter what, your level of intoxication will decrease over time. The more time passes, the less drunk you’ll be, and the safer it will be to drive. You can always increase your safety by waiting a bit longer before getting on the road.
Drunk driving remains a serious problem, with 29 people in the United States dying every day as a direct result of alcohol impairment. Understanding how alcohol functions in the body and how DUIs are treated in the legal system can help you ensure you’re in good condition to drive. But if you want to play it safe, always get a designated driver, even if you think you’re safe to drive. The extra caution won’t hurt, and could end up saving a life—including yours.