Whether you’re travelling to the States on vacation, or actually live in America, if you’re planning to drive, it’s important to remember that alcohol can slow you down and affect your body’s responses, making your driving unsafe.

Learning the facts on drunk-driving and the DUI law in the States can help you prevent putting yourself and others at risk when you hit the road.

What is DUI?

Although DUI (driving under the influence) is more commonly associated with alcohol related incidences, it can also refer to driving whilst under the influence of any other substances, legal or illegal, that could result in impaired driving.

In the case of alcohol, governments set a ‘legal limit’ which serves as an indication of alcohol’s predictable effects on driving and whether you’re fit to drive or not. However, even small amounts of alcohol can affect your ability to drive, so the only safe advice is to avoid drinking any alcohol if you are driving.

What is the legal alcohol limit?

The legal alcohol limit in the US is the same as in the UK. Driving under the influence of alcohol, often referred to as drunk-driving, is defined by American law as driving a vehicle whilst having a BAC (blood alcohol concentration) of .08 grams per deciliter of blood (g/dL) or higher1 - which is the equivalent to UK’s legal limit of 80 milligrammes of alcohol per 100 millilitres of blood. So, if you’re caught driving with this BAC level or higher you’ll be committing a DUI offense and putting yourself and others at risk.

As crash risks increase dramatically after such BAC level, all 50 states consider anyone driving with a BAC of .08 g/dL or higher to be drunk-driving2 (though Utah’s BAC limit is set to change in December 2018 to .05 g/dL).3.

How can alcohol affect my driving?

If you’re planning a night out, or have stayed for drinks after work and don’t know whether to take a taxi or drive, it's important to remember that alcohol can slow you down and affect your body’s responses, putting you and others at risk.

There are many functions we rely on to drive safely that alcohol can affect, for example:

  • The brain takes longer to receive messages from the eye
  • Processing information becomes more difficult
  • Instructions to the body's muscles are delayed, resulting in slower reaction times
  • You can also experience blurred and double vision, which affects your ability to see things clearly while you are driving
  • And, you’re more likely to take potentially dangerous risks because you can act on urges you normally repress4.

Dangers of drunk-driving

Because alcohol has an affect on our reactions and decision-making abilities, drunk-drivers may make decisions that could result in dangerous consequences for themselves and others.

DUI is considered to be a serious offense and steps are being taken to reduce the number of alcohol-impaired drivers on the road. However, whilst strict BAC limits and drunk-driving penalties exist across the United States to ensure safe driving on the roads, in the year 2016 there were 10,497 fatalities involving drunk-drivers.5

What are the DUI penalties?

Despite all states agreeing on the drunk-driving limit being .08 g/dL, the punishment for a DUI offense varies across the US.

Generally, being caught drunk-driving can result in some pretty costly fines and legal fees. In addition to this, if a driver is caught with a high BAC the punishment could be more severe. Although the law changes across states, other common penalties are:

  • Driver’s licence suspension, which can last between 90 days to 1 year depending on the state
  • An ignition interlock system being installed on your vehicle. Similar to the traditional breathalyzer, this is a breath test device that is fitted to the ignition. The vehicle will not start unless the driver blows into the device and they usually have a pre-set BAC limit of .02 g/dL6
  • Vehicle impoundment7
  • And, in cases where a serious injury or death has occurred, the drunk-driver could be prosecuted and convicted with a prison sentence

How much can I drink and stay under the DUI limit?  

There is no fool-proof way of drinking and staying under the DUI limit. An individual’s BAC level changes from person to person and depends on a variety of factors such as:

  • Your weight, age, sex and metabolism (the rate your body uses energy)
  • The type and amount of alcohol you’re drinking
  • What you’ve eaten recently
  • Your stress levels at the time

Even small amounts of alcohol can affect your ability to drive, so if you’re driving the only safe advice is to avoid drinking alcohol completely.

How to avoid drunk-driving?

  • Arrange within your group of friends who's going to be the designated driver - someone who abstains from alcohol on a night out so they can drive the rest of their friends home safely.
  • If you live somewhere with good public transport links take advantage of them. If you’re planning on staying out beyond the last train, subway or bus, make sure you’ve got a couple of taxi phone numbers at hand or arrange with a sober friend in advance to pick you up.
  • If you’re with someone who is over the DUI limit, then make sure they don’t drive. Take away their keys and call them a taxi.
  • If you have no option but to drive, stick to non-alcoholic beers, mocktails or sodas.
  • Not every night out has to involve a bar or club - you could book a table at a restaurant or try an alcohol-free night.
  • You could choose to have a drink-free day, meaning you’d be able to drive safely at any time.
References

1. Nhtsa.gov website. drunk-driving. Available at https://www.nhtsa.gov/risky-driving/drunk-driving

2. Ghsa.org website. Alcohol Impaired Driving. Available at https://www.ghsa.org/issues/alcohol-impaired-driving

3. Utah.gov website. Commissioner Squires Releases Information on .05 BAC Change. Last reviewed March 2017. Available at https://publicsafety.utah.gov/2017/03/31/commissioner-squires-releases-information-on-05-bac-change/

4. C. Fernando Valenzuela. ‘Alcohol and Nerotrasmitter Interactions’, Alcohol Health & Research World. Available at: http://pubs.niaaa.nih.gov/publications/arh21-2/144.pdf

5. Nhtsa.dot.gov website. Traffic Safety Facts. Last reviewed October 2017. Available at https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/812450 

6. Nhtsa.gov website. drunk-driving. Available at https://www.nhtsa.gov/risky-driving/drunk-driving

7. Gsha.org website. Alcohol - Impaired Driving Laws by State. Last reviewed April 2018. Available at https://www.ghsa.org/sites/default/files/2018-04/DrunkDrivingLaws_040418_0.pdf