DUI/DWI Drunk Driving

What is Drunk driving?

Drunk driving or drinking and driving is the act of operating a motor vehicle after having consumed alcohol (ethanol) or other drugs, to the degree that mental and motor skills are impaired. It is illegal in most jurisdictions within the U.S..

The specific criminal offence is usually called driving while intoxicated (DWI) or driving under the influence [of alcohol or other drugs] (DUI). Such laws may also apply to boating or piloting aircraft.

According to the National Highway Traffic Safety Administration (NHTSA), 17,419 people died in 2002 in alcohol-related collisions, representing 41 percent of total traffic deaths in the United States. Over 500,000 people were injured in alcohol-related accidents in the US in 2001. Alcohol-related is defined to include any driver, passenger or pedestrian involved in a fatal crash who has any trace of alcohol or suspicion of alcohol usage. According to the NHTSA, no other country uses these criteria in their statistical computations.

DUI, DWI, Drunk driving laws?

Most states in the U.S. designate a "per se" blood or breath alcohol level as the threshold point where a person is presumed to be impaired. The most common blood alcohol content (BAC) "legal limit" in the United States is 0.08 (i.e., 80 mg of alcohol in 100 ml of blood). Some states include a lesser charge — often known as driving while impaired — at a BAC of, say, 0.05 or above but less than the legal limit for the more serious charge (only Delaware still uses a more lax limit: 0.10). Prior to wider emphasis on drinking and driving in the 1980s, standards of 0.12 were also in place in some states. The legal limit for aircraft pilots in the U.S. is set at 0.04. Many states observe a much stricter standard — known in some of them as "TCP," standing for "Trace Constitutes Positive" — for drivers under the age of 21, which, since 1989, has been the uniform minimum purchase age for alcoholic beverages throughout the nation (prior to that year about half of all U.S. states formerly observed a lower drinking age, most commonly 18; the trend toward raising the age commenced in the late 1970s, with much of the impetus for doing so provided by a federal law passed in the mid-1980s mandating a reduced allocation of federal highway funds to any state which refused to raise the age to 21).

Unlike DUI cases that involve alcohol, there is no "per se" or legal limit that is employed for persons accused of driving under the influence of prescription medication or illicit drugs. Instead, the key inquiry focuses on whether the driver's faculties were impaired by the substance that was consumed. The detection and successful prosecution of drivers impaired by prescription medication or illegal drugs is therefore quite difficult. Similarly, although urinalysis toxicology screens can detect the presence of such substances in the driver's bloodstream, these analyses are unable to demonstrate that the substance was actually causing impairment at the time of driving. In response to these problems, several jurisdictions are currently considering legislation that would establish "zero tolerance" laws for those drivers arrested for DUI and found to have drugs or medication in their system. Additionally, technology is being developed for the purpose of administering roadside or laboratory tests that can detect the actual level of a controlled substance in an individual's body.

Many jurisdictions require more serious penalties (i.e., jail time, larger fines, longer DUI program, the installation of ignition interlock devices) in cases where the driver's BAC is over 0.20, or even 0.15 in some places. These additional sanctions are an attempt to deter and punish the operation of a vehicle at extremely high BAC levels and the concomitant danger posed to the safety of persons and property by heavily impaired drivers. In many cases, the reason given for these additional sanctions is because an average person would have passed out from that much alcohol. To be able to drive at that level, a person has to have gotten drunk regularly for years, to increase his/her alcohol tolerance, and therefore is likely to have driven drunk repeatedly. However, since there is currently no standard test to measure alcohol tolerance, proponents of high-BAC additional penalties point to some studies that indicate that high-BAC offenders are more likely to be involved in a crash and more likely to recidivate. Critics of such laws point out that, due to the wide variation of alcohol tolerance, people with a high tolerance will suffer the additional penalties, even though they may be much less impaired than people with a low tolerance that were driving with a much lower BAC.

Some U.S. states also increase the penalties for drunk driving (even to the point of making it a felony) if certain other aggravating circumstances besides a very high BAC are present, such as if the drunk driver caused an accident requiring the hospitalization of another person lasting greater than a specified period of time (often 72 hours), in cases where an accident resulted in property damage exceeding a certain amount (often $500), or where the driver has a prior (and relatively recent) conviction for drunk driving. In addition, most states observe administrative laws that further penalize people convicted of DUI, typically enforced by the department that issues driver's licenses, usually titled Department of Motor Vehicles (DMV), or Department of Licensing. Also, in many states, persons under 21 who purchase, or even attempt or conspire to purchase, alcohol can have their driving privileges suspended (if they already are licensed drivers) or delayed (if not) even if they were not caught actually driving while intoxicated.

Typical DUI arrest.

The following is what can happen when a law enforcement officer has a reason to suspect a driver is intoxicated. Some possible reasons are erratic driving, poor coordination, and/or the presence of the smell of alcohol.

Field sobriety test

The officer will administer one or more field sobriety tests (FSTs). Some common FSTs include having the driver:

* try to walk in a straight line, heel-to-toe.

* tip his or her head back with eyes closed and try to touch the tip of the nose with the index finger.

* stand on one foot.

* reciting all or part of the alphabet.

FSTs are better at determining the level of impairment than they are at estimating the driver's BAC.

The (US) National Highway Traffic Safety Administration has scientifically determined that three FSTs are statistically reliable in detecting impaired drivers. These three "standardized" tests are the "Walk and Turn" test, the "One-leg Stand" and "Horizontal Gaze Nystagmus" in which a law enforcement officer observes the discrete movements of a person's eyes when tracking a stimulus across their field of vision.

Chemical test

If arrested, the driver is brought to the police station, and given one or more chemical tests: breath, urine, and/or blood. Breath test results are usually available immediately and are sometimes given before the actual arrest takes place; urine and blood samples are sent to a lab to determine the BAC. In some jurisdictions, refusing to take a breathalyzer test is an offense in itself, often creating an automatic assumption of guilt under the law.

Chemical tests are better at determining the driver's BAC than they are at estimating the level of impairment, but their accuracy is disputed by some (see blood alcohol test assumptions). In any case, tests can only determine the BAC at the time the test is taken, which sometimes can be higher than when the vehicle was actually operated, in the case of a driver who drank a large volume immediately before driving.

Next step

If it is determined that the person is not legally intoxicated, they might be released without any charges. However, many jurisdictions have charges which don't require a particular BAC, and tests for some drugs (such as GHB) will not show up in a test designed for alcohol.

Most of the time, the driver will either be kept in a holding cell (the "drunk tank") until they are deemed sober enough to be released, or sent to jail to wait for their first court hearing (or until they can get bailed out).

What is the BAC legal limit?

Blood alcohol content (or blood alcohol concentration), often abbreviated BAC, is the concentration of alcohol in blood, measured, by volume, as a percentage. For example, a BAC rating of 0.20 means 1 part per 500 in an individual's blood is alcohol. In many countries, the BAC is measured and reported as milligrams of alcohol per 100 milliliters of blood (mg/100ml).

Number of drinks consumed is a poor measure of intoxication, because of variation according to body weight. One drink (unit of alcohol) will increase the average person's BAC to roughly 0.04, but there is much variation according to body weight, gender and body fat percentage. Furthermore, neither BAC nor the number of drinks consumed are necessarily accurate indicators of the level of impairment. Individual alcohol tolerance varies, and can be affected by genetic or nutritional factors, drugs, other degrees of impairment, and long-term heavy drinking.

Alcohol content in blood can be directly measured by a hospital laboratory. More commonly, for law enforcement purposes, BAC is estimated from breath ethanol content measured with a machine commonly referred to as a Breathalyzer (even though that is just the trademark of one manufacturer of the devices).

For purposes of law enforcement, BAC is used to define intoxication and provides a rough measure of impairment. Although degree of impairment may vary among individuals with the same BAC, the BAC has the advantage of being simpler to measure objectively, and therefore harder to contest, than impairment of driving.

Most countries disallow operation of motor vehicles and heavy machinery at prescribed levels of BAC, which vary both by country and by situation. In Sweden, driving with a BAC rate of over 0.02 is illegal. By contrast, the policies of the United States are much more liberal: In one state, a BAC rating as high as .099 is considered not intoxicated, though the federal government is pushing for a reduction of the limit to 0.08. In some states, drivers under 21 (the American drinking age) are considered legally impaired at lower levels (perhaps 0.02, or even a mere trace) as part of a zero tolerance policy.

In Australia, the limit is 0.05 in most states and territories, and either 0.02 or zero for inexperienced drivers (learner drivers or those on probationary licenses). It is enforced by random breath testing.

Despite the liberal intoxication limits of many countries, one should not assume that driving with a BAC rating of, say, .079 is as safe as driving while sober. At a BAC rating of 0.05, the probability of a driver having an accident is more than four times its base level. Despite this, some drivers believe their driving actually improves with small amounts of alcohol. This assertion is false, because their ability to accurately judge the quality of their driving (measured by actual motor competence) deteriorates.

Unless a person has developed a high tolerance, a BAC rating of 0.20 represents very serious intoxication (most first-time drinkers would be passed out by about 0.15), and 0.35 represents potentially fatal alcohol poisoning. 0.40 is the accepted LD50, or lethal dose for 50% of adult humans. For a long-time, heavy drinker, those numbers can at least double. In extreme cases, individuals have survived BAC ratings as high as 0.914, but only with medical attention.

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