It's not a question of whether you are legally intoxicated, it's a question of whether or not it is safe to drive when you have consumed any amount of alcohol. Research shows that impairment begins long before a person reaches the blood alcohol concentration level necessary to be guilty of drunken driving.

What is the legal limit? In all 50 states, a blood alcohol concentration (BAC) level of .08 is considered the legal limit. The consumption of four drinks in a 180 pound man can reach this limit and only 2 drinks for a 120 pound female. Take note that there are many factors that will affect your Blood Alcohol concentration (BAC). Size, gender, physical condition, how much you have eaten, how much sleep you have had, are you taking any medications, and the actual alcohol content of your chosen "drink."

A "drink" consists of either one shot of liquor, a five-ounce glass of wine or one beer. All of these contain the same amount of alcohol.

At a .08 BAC level, drivers are so impaired that they are 11 times more likely to have a single-vehicle crash than drivers with no alcohol in their system. But 25 years of research has shown that some impairment begins for both males and females even after one drink. .02 BAC Level At the .02 blood alcohol concentration level, experiments have demonstrated that people exhibit some loss of judgment, begin to relax and feel good. But tests have also shown that drivers at the .02 level experience a decline in visual functions, affecting their ability to track a moving object, and experience a decline in the ability to perform two tasks at the same time.

But tests have also shown that drivers at the .02 level experience a decline in visual response affecting their ability to track a moving object, and experience a decline in the ability to perform two tasks at the same time. This level also might also experience lightheadedness. These changes may be very subtle and barely noticeable to the person who has had only one drink, but in an emergency situation while behind the wheel of a motor vehicle, they could cause the driver to react (or not react) as they would without having had a drink.

.05 BAC Level At the .05 BAC level, people begin to exhibit exaggerated behavior, experience loss of small-muscle control -- such as being able to focus their eyes quickly -- have impaired judgment, lowered alertness and a release of inhibition. If someone with a BAC level of .05 gets behind the wheel, they would be operating the vehicle with reduce coordination, a further diminished ability to track moving objects, more difficulty in steering and a markedly reduced response in emergency situations.

.05 BAC Level - At the .05 BAC level, people begin to exhibit exaggerated behavior. They may experience loss of small-muscle control such as being able to focus their eyes quickly and suffer impaired judgment, lowered alertness and a release of inhibition.

If someone with a BAC level of .05 gets behind the wheel, they would be operating the vehicle with a further reduction of coordination. The ability to track moving objects would grow harder and there would be more difficulty in steering. The driver would have a markedly reduced response in emergency situations.

A driver with a BAC of .08 will find it more difficult to concentrate, judge the speed of the vehicle, experience reduced information processing capability and exhibit impaired perception. At a .08 BAC level, drivers are impaired to the point that they are 11 times more likely to have a single-vehicle crash than drivers with no alcohol in their system. But 25 years of studies have shown that some impairment begins for both men and women even after only one drink.

A driver with a BAC of .08 will find it more difficult to concentrate and might even have some short term memory loss. There is difficulty in judging the speed of the vehicle, and the experience of reduced information processing capability. They will exhibit impaired perception. At a .08 BAC level, drivers are so effected that the relative risk of a single- vehicle crash is 11 times more likely than drivers with no alcohol in their body. This risk is 52 tines higher for males! But 25 years of research has shown that some impairment begins for both men and women even after one drink.

For the drinker, the above impairments may be hardly noticeable at the time, but the slow reaction times that they can create could be fatal in a emergency driving situation. No matter the situation, it is not a good idea to drive no matter how much or how little that you have had to drink. Further consideration is alcohol tolerance. Alcohol affects people differently. Some people have a higher response to drinking alcohol than others. Simply put, Those drinkers with a high response to alcohol can experience signs of impairment at the .02 BAC level whereas others do not experience effects until the .05 level.

Since this tolerance can vary so widely form person to person, in many states a driver can be arrested for impaired driving even if their blood alcohol concentration is below what is considered legal. Using the basis of reaction of the driver and their behavior, law enforcement can make the decision if he believes there is probable cause. With all of the risks associated with getting behind the wheel after having even just one drink, the choice to not have that drink is obviously the right one to make.