Anyone who has ever watched "Cops" or other police procedural television shows has probably seen an example of the roadside tests administered when an individual is suspected of driving while intoxicated. While breathalyzer machines and blood tests are extremely scientific ways to determine a person's blood-alcohol-level, the field sobriety test often helps establish a reasonable cause for the officer to make an arrest.
Typical roadside tests measure an individual's balance, dexterity, and mental sharpness. A person who is intoxicated beyond the legal limit will often struggle with tasks that would not be difficult for an individual who is completely sober. It is up to the arresting officer to determine which sobriety tests will be administered in the event of a traffic stop.
One common roadside test is to have the suspected drunk driver balance on one foot at a time. Significant amounts of alcohol can have serious effects on a person's balance, and the inability to stand on one foot is a big "tip-off" to any officer of the law. Another physical test includes walking a straight line, while placing one foot in front of the other. Again, this task should be simple for someone who has not consumed alcohol, but difficult for one who is intoxicated.
Tests that determine manual dexterity often include, using one's hands and fingers to demonstrate sobriety. It would seem that the simple act of touching your finger to your nose could never be difficult, but a person who is drunk often cannot mimic the motion in a precise manner. Officers may also have the person try to touch each finger to their thumbs, again checking for precision in the small movements. Other tests, such as the "eye test", where an officer will ask a person to follow a moving pen with their eyes, are designed to help the officer other physical signs of intoxication.
Tests that require a level of mental sharpness may include counting backwards from a certain number, or reciting the alphabet backwards. Interestingly enough, some intoxicated individuals find themselves unable to perform the tasks required in even simpler manners (such as reciting the alphabet in the correct order). Officers can also discern a level of intoxication from the person's manner of speech, paying close attention to slurring, mispronunciations, and lack of clarity in their words.
Although blood testing and breathalyzer analysis may be more precise methods of determining the sobriety of an individual, the roadside tests administered by officers of the law are effective in establishing probable cause for arrest.
Article Source: http://EzineArticles.com/?expert=Joseph_Devine