Impaired Driving: Laws, Penalties and Consequences
Driving Under The Influence

Driving Under The Inlfuence: Know The Facts About Drugs & Alcohol

Updated Dec. 25, 2020

Impaired driving is without a doubt the biggest threat road users in the United States face today. As we have seen throughout previous modules of this course, driving defensively and avoiding roadway collisions demands mental acuity and keen motor skills. When a driver is impaired by alcohol, drugs, fatigue or illness, they are not able to think as clearly, move as precisely or accurately perceive the situation on the road around their vehicle. As a result, they are far more likely to make a serious error that results in a traffic collision.

In this section, we explore the two most widespread and dangerous causes of driver impairment: alcohol and drugs. You will learn how these chemical substances affect your body and how this will ultimately impair your ability to drive safely. In addition, we discuss the laws relating to driving under the influence of alcohol or drugs, and the likely legal and personal consequences of driving while impaired.

Alcohol and drug awareness must feature prominently in your driver’s education program, as being a young novice driver, you are more susceptible to the effects of driver impairment than more experienced motorists. Moreover, most teenagers and young adults are exposed to alcohol and drug use through their friends and wider social circle at some point. Therefore, you may be tempted to try these substances yourself. If you understand how drinking alcohol or taking drugs will affect your physical, mental and emotional state, you can protect yourself from:

  • Poisoning and overdose
  • Long-term health consequences
  • Driving under the influence

If you are under 21 years old, driving with any alcohol in your bloodstream is illegal. You do not have to be blind drunk for your driving ability to be impaired by alcohol. A single sip of an alcoholic beverage can alter your mental state enough to slow your reaction time and leave you more likely to engage in risky behavior. Teenage drivers are particularly susceptible to this effect due to their lack of driving experience and low tolerance for alcohol.

As a responsible young adult, you must respect the law and say no to alcohol and drugs. If you DO choose to drink or take drugs, don’t drive.

These are simple rules to follow. Break them and you may end up losing your driving privileges, or worse, your life.

Driving under the influence of alcohol

Alcohol is a dangerous, intoxicating substance. It will alter the way your mind works and impair your ability to control your own body – let alone a car! Unfortunately, society normalizes alcohol consumption. We are led to believe that alcohol is relatively safe and is a normal, even beneficial part of everyday life. Slowly, our misconceptions about alcohol are changing. Fewer people are choosing to drink and tougher laws allow federal and statutory governments to crack down on alcohol abuse and alcohol-related offenses, like driving under the influence (DUI). Despite this progress, alcohol is still known to be a causal factor in around one-third of all traffic-related deaths in the United States. If you choose to drink and drive or associate with people who do, you – or somebody you care about – could easily end up part of this statistic.

What are the current DUI laws?

In all 50 states and the District of Columbia, driving under the influence of alcohol is against the law and will result in severe penalties. Person’s under 21 are not permitted to operate a vehicle with ANY alcohol in their blood, whereas adults are legally permitted to drive with a blood-alcohol level of up to 0.08% in most states. You can find out what this reading translates to in terms of actual alcohol consumption and learn how to estimate your blood alcohol concentration (BAC), in our modules on BAC and DUI laws.

How much alcohol is safe?

It is important to understand that “legal” is not the same as “safe”. In practically every state, adults over 21 can legally operate a vehicle with a blood alcohol concentration of 0.03%, 0.05% or even 0.07%. Does this mean they will not be impaired by alcohol at these BAC levels? Absolutely not. Alcohol intoxication and impairment can start to take hold at as low as 0.02% or 0.01%.

From the moment you take your first sip of an alcoholic drink, alcohol will start to seep into your bloodstream through blood vessels in the mouth and make its way around the body to your brain. Here, even trace amounts of alcohol can have a potent chemical effect on the brain, altering cognition and slowing down bodily functions in a myriad of subtle (and sometimes, not-so-subtle) ways. Our “driving under the influence of alcohol” module explains the precise mechanisms behind:

  1. Alcohol absorption (how you become intoxicated) and,
  2. Alcohol elimination (how alcohol is expelled from your body and how long this will take on average).

The effects of alcohol intoxication

The short-term effects of alcohol intoxication vary a little from person to person. Most people experience a sense of well-being, euphoria or joy quite soon after starting to drink. Your mood will continue to be affected the more alcohol you consume but the results will be unpredictable. An alcohol intoxicated person can experience rage, despair and suicidal inclinations just as easily as they can experience excitement and happiness. As alcohol starts to disrupt messages sent between the brain and the rest of the body, you will experience:

  • Blurred vision
  • Slurred speech
  • Poor physical coordination
  • Poor muscle control
  • Impaired memory
  • Mental confusion

These effects of alcohol on your driving ability will worsen the more intoxicated you become. If you continue to drink, you will probably vomit and pass out. This level of drunkenness is alcohol poisoning territory.

The long-term effects of alcohol abuse

While any discussion of driving under the influence will predominantly focus on the short-term effects of alcohol consumption, we cannot ignore the long-term health implications of regular drinking. Alcohol is a poisonous substance that, over time, can destroy every vital organ and system in your body. Your liver is most at risk, as it has the most “hands-on” role in removing alcohol from the bloodstream. When liver cells are forced to work too hard, or for too long, they will eventually begin to wither and die.

You can read all about the health consequences of alcohol abuse in our full-length module on this topic. For now, just know that long-term, regular drinking can eventually result in:

  • Liver cirrhosis and failure
  • Heart disease
  • Stroke
  • Chronic digestive issues
  • Permanent brain damage

Moreover, alcohol can cause physical addiction and mental dependency. A person suffering from alcohol addiction would continue to drink, even knowing that alcohol is slowly ravaging their health and killing them.

The alcohol-impaired driver

Alcohol affects the system of nerves and cells through which messages are passed around the body. When this system is disrupted, messages are slowed, blurred or cut-off altogether. The result is a body-wide break down of normal functions and processes. Alcohol intoxication will impair your senses, thought processes (cognition) and physical movements. Any one of these impairments would make you unfit to drive. Together, they have a devastating effect on driving ability.

  1. 1

    Sensory impairment.
    When your senses are impaired, you cannot form a complete and accurate picture of what is going on around your vehicle.

  2. 2

    Cognitive impairment.
    When your cognition is impaired, you cannot decide on appropriate responses to changes in the driving environment.

  3. 3

    Physical impairment.
    When your movements are impaired, you cannot execute ordinary driving maneuvers as quickly, or as smoothly as you would usually.

As a result, alcohol-impaired drivers typically travel at unsafe speeds, struggle to maintain an appropriate lane position, do not leave enough space around the vehicle, fail to communicate with other road users and disregard traffic control devices.

Alcohol changes your personality

One of alcohol’s most dangerous effects is its ability to alter the drinker’s personality and emotional state. If you were to ask a DUI offender whether they set out to drink and drive, the answer would probably be “no”. Most people understand the dangers of drink driving and would never dream of getting behind the wheel while intoxicated. Unfortunately, an intoxicated person is liable to make very different decisions to a sober person, as alcohol impairs judgment.

While under the influence of alcohol you may choose to drive if that option is available to you, and you feel you can get away with it. Drinking alcohol makes people:

  • More inclined to take risks
  • More inclined to underestimate danger
  • Less afraid of negative consequences
  • Less aware of their own physical and mental state

In addition, alcohol can distort emotions and lead to dangerous, “heightened” emotional states. If you were to drive while feeling depressed, overly excited or angry, your behavior on the roads is likely to increase the risk of an accident or collision occurring. Remember that any substance which changes the way you feel will also change the way you drive.

Driving under the influence of drugs

The next section in this block deals with driving under the influence of drugs – something many people do without even realizing it. The word “drug” could refer to:

  • Illegal substances like cocaine and marijuana.
  • Legal substances that are used for medical purposes, like anti-depressants and pain killers.
  • Other substances that we do not necessarily think of as “drugs”, but which have a mind-altering effect, like nicotine or caffeine.

If you smoke before driving, sip coffee behind the wheel or are taking regular allergy medication, you are driving under the influence of drugs. However, you are not driving under the influence in an illegal sense, unless the substance you are taking has caused mental or physical impairment. We will discuss this complex issue in full later. All you need to know now is that you can be convicted of DUI if you are driving erratically and later test positive for any potentially impairing substance, including over the counter medicines.

Drug misuse penalties and DUI

Depending on the state in which the crime was committed, you may be charged with DUI or DWI if you are caught driving under the influence of drugs. Usually, drug-impaired driving is treated equally as harshly as alcohol-impaired driving. While it may not seem fair, state laws do not generally distinguish between “accidental” impairment (whereby a person has unintentionally impaired their driving ability by taking prescribed medication) and drug-impairment involving illicit or misused substances. Keep this in mind and make sure you monitor yourself for signs of impairment when taking ANY drug, before getting behind the wheel. The main message to take away from this section of the module is that all drugs have the potential to be dangerous and cause impairment.

If the drug you have taken is illegal, or you are using it illegally, you will also have to deal with other drug charges in addition to DWI, if you are caught driving under the influence. Punishments for drug charges vary greatly around the United States and will be partly determined by where that drug sits on the Controlled Substances Act.

The controlled substances act

If there are laws concerning how, when and under what circumstances a drug can be manufactured, sold or used (as is the case with most recreational drugs and pharmaceutical medications), it will be listed in one of five “schedules” on the controlled substances act. Knowing where a drug is positioned on the substances act can give you a rough idea of its potential to cause harm and the likely legal consequences of misusing it. You can find out about scheduled drugs and the controlled substances act in a later, dedicated module.

All scheduled drugs can cause health problems and overdose when taken in large enough quantities. The same is true of unscheduled drugs (like caffeine, nicotine and alcohol), despite them being readily available. Equally, all drugs can impair your driving ability. Remember, any substance that alters the functioning of the brain and body will also alter the way you drive. The precise impairments you experience will depend on the type of drug you have taken.

Drug types and driver impairment

Do you know the difference between stimulant, depressant and hallucinogenic drugs? While every drug creates a unique chemical reaction in the body which leads to different effects, most drugs can be classified as either a stimulant, depressant or hallucinogen, based on their main biological action.

  1. 1

    Drugs such as cocaine, Adderall, methamphetamine and MDMA are stimulants, in that they make bodily processes work faster. Behind the wheel, this effect often results in speeding, tailgating, aggressive behavior and disregard of road rules.

  2. 2

    Drugs like heroin, oxycodone, Xanax and Nembutal have the opposite effect, as they are depressants. By slowing down bodily processes, these substances can cause drowsy driving, sloppy maneuvering, poor space management and failure to adhere to traffic control devices.

  3. 3

    Hallucinogenic drugs like marijuana, LSD, psilocybin mushrooms and dextromethorphan can cause any of the above effects, plus hallucinations. Seeing or experiencing things that are not real while driving a car would lead to a wide range of dangerous and erratic behaviors!

The mental and physical effects of common stimulants, depressants and hallucinogens are explored fully during the drugged driving chapter. We also take an in-depth look at how these effects translate to driver impairment and increased risk on the roadway.

The dangers of inhalants

Inhaling fumes from paint thinner, glue, body sprays and other similar products that were not designed for human consumption is a widespread and extremely dangerous form of drug abuse, common among younger teenagers. The chemicals in these products can cause anything from euphoria and fits of giggles to unconsciousness and instantaneous death. Abusing inhalants can result in extreme, unpredictable impairments to your driving ability. Learn more, in our dedicated module on the dangers of inhalants.

Combining drugs with alcohol

Drug-alcohol interactions are responsible for thousands of preventable deaths around the United States every year. In some cases, the chemical reaction between two or more intoxicating substances is enough to cause death by overdose. In others, death occurs as a result of a catastrophic traffic collision, because the driver did not realize that using alcohol alongside the drug would dramatically increase driving impairment.

The precise effects of combining alcohol with a drug (or indeed, a drug with another drug) will depend on the types of substance involved. Consuming alcohol and taking a drug puts enormous strain on the body and prolongs intoxication, as the liver will have two interacting substances to filter out of the bloodstream. Drinking while taking drugs is often extremely harmful to your health, even if we’re just talking about a glass of wine alongside your usual prescription pain medication.

What many drivers do not realize is that very small amounts of alcohol can lead to severe mental and physical impairment, when combined with certain drugs – including prescription and over-the-counter medication. If your driving behavior is noticeably impaired and a law enforcement officer stops you, you will likely be charged with driving under the influence even if you are under the legal BAC limit and the drug you have taken is prescribed to you by a doctor. Remember that drug-impaired driving is illegal, even if the drug you have taken is not.

Impaired driving in the United States

It is difficult to accurately measure the consequences of alcohol and drug-impaired driving in the United States, though we do know it costs the country billions of dollars and takes thousands of innocent lives every year. Alcohol-impairment is linked to around 10,000 traffic collision fatalities annually. In many of these collisions, illegal or prescription drugs were also a causal factor. The true human cost of drug-impaired driving is hard to quantify, as many intoxicating substances cannot be tested for outside of a laboratory. It is probable that many fatal traffic collisions that don’t involve alcohol do involve a driver that is impaired by an undetected drug.

Impaired driving laws and penalties

The final section of “Driving under the influence” explains your responsibilities regarding drugs and alcohol as a driver, plus the legal ramifications of breaking a DUI or DWI law. This will include differences in terminology, how crimes are classified and the importance of understanding implied consent. Due to implied consent laws, you can be prosecuted for refusing to let a police officer test your blood alcohol level during a routine traffic stop.

If you are found guilty of driving under the influence or driving while intoxicated, your penalties will almost certainly include a fine and a license suspension. A prison sentence is another likely outcome of a DUI conviction, though this punishment is typically reserved for serious DUI crimes and repeat offenses. Other possible penalties for drunk-driving and drug-impaired driving convictions include:

  • Community service
  • Participation in an alcohol awareness program
  • Restricted driving privileges (whereby your vehicle may only be used for certain purposes, or with an ignition interlock device)

Related alcohol laws

“Driving under the influence” is not the only alcohol-related crime you need to know about. In many states, it is also a crime to:

  • Have an open container of alcohol in a vehicle
  • Serve alcohol in a bar if you are under 21
  • Supply somebody who is under 21-years old with alcohol
  • Attempt to purchase alcohol if you are under 21
  • Misrepresent your age

Like driving under the influence, the penalties you may receive for breaking these laws vary state by state. There are also exceptions to these laws in most of the states where they apply. Learn more about related alcohol laws in “Impaired driving: laws, penalties and consequences” and your driver’s education manual.

Teen impaired driving laws

An under 21-year old who is caught driving while intoxicated will likely be charged with possession and consumption of alcohol, on top of the DWI. This is possible in many states, even if you have no alcohol on your person or in the vehicle, as you still “possess” the alcohol which is in your blood.

As a young driver, it is important to remember that the legal BAC limit for adults does not apply to the under 21s. While you are underage, you will be guilty of driving under the influence if you are found operating a vehicle with ANY measurable level of alcohol in your blood. You could end up with a DUI conviction simply by taking too much cough medicine or swallowing your mouthwash by mistake!

Every state takes a slightly different approach to restricting teenage drinking and punishing underage DUI offenders. All the information you need is covered over the course of the impaired driving module. Make sure you read through everything thoroughly, so you can stay on the right side of the law. Wherever you reside in the United States, you can bet that teenage drinking and DUI offenses will be dealt with swiftly and harshly. Incidences of teenage drink-driving are less common than they were ten or 20 years ago, though it is still an enormous problem. Underage drivers may be less likely to commit a drink-driving offense than adult drivers (largely due to tougher restrictions on alcohol) but they are still substantially more likely to die in a fatal collision if they do drink and drive.

The consequences of drunk driving

Being injured, killed or arrested are not the only potential negative consequences of driving while impaired by alcohol or drugs. Causing a drunk driving collision can completely alter the course of a driver’s life and it is never for the better. If you are arrested and convicted of DUI, you will have to live with the negative backlash of your actions for a very long time. This often includes:

  • Rejected college and job applications
  • Enormous financial expense (lawyers, fines, property damage, court costs)
  • Social problems (lost friendships, being treated differently by your family and the wider community)
  • Mental health problems (depression, post-traumatic stress disorder)
  • Lost driving privileges

You stand nothing to gain from getting behind the wheel while intoxicated, but you do have a great deal to lose. Fortunately, protecting yourself from these devastating consequences is blissfully simple: do not drink and drive.

Impaired driving prevention

You would never attempt to drive with a broken leg, or while severely sleep-deprived, and you must adopt a similar zero-tolerance attitude towards driving while impaired by drugs or alcohol. Nobody is forced to drink and drive – there are always other options.

If you are going to an event that may involve alcohol, planning ahead is the key to staying sober, or staying out of the driver’s seat. Choose a designated driver, call a cab or sleepover at a friend’s house but never trust a drunk person with your car keys (especially if you are the drunk person). As you will see over the course of this module, alcohol and drugs can warp a person’s mental state to the extent that they make stupid, dangerous decisions – like driving themselves home while intoxicated.

There is a reason that people often regret their behavior after a night out drinking. The person you are while under the influence of alcohol or drugs is not the person you are while sober. Where drinking alcohol is concerned, the only 100% safe decision is not to drink at all!

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