A sobriety test is used to check if a person is intoxicated or under the influence of drugs. These tests are often administered by law officers if drunk driving is suspected. Failing a sobriety test may result in drunk driving charges, which can carry penalties of fines, community service, or jail time.
Many sobriety tests measure coordination ability rather than actual blood alcohol content. These tests are often controversial, as most have a high rate of false positives and are based on the discretion of the test administrator, rather than on provable evidence. Sobriety tests may include performing physical tasks, such as walking in a straight line, standing on one leg, or following a light using only the eyes. While these tests are useful in winnowing out the severely inebriated, they can also trip up those who are naturally uncoordinated or nervous about the test.
A more accurate type of sobriety test uses a small device, often called a breathalyzer, to give an estimate of blood alcohol levels. Since many regions have alcohol laws based on blood alcohol content, these tests clearly indicate whether a person is over the legal limit. Breathalyzer tests require the user to blow air into the device, which then measure the amount of alcohol in the breath. It is important to remember that even if a person is under the legal allowed limit, any alcohol intake can lower coordination and motor responses, making accidents more likely.
Despite the higher accuracy of a breath sobriety test, the device is not foolproof. Many models are extremely sensitive to temperature changes and can easily malfunction if not calibrated correctly. In addition, some substances, such as mouthwash, contain alcohol that can create a false positive on a breath sobriety test.
There is some controversy as to the use of a field sobriety test constituting an illegal search. According to some legal interpretations, a police officer must have probable cause to require a breath test or other sobriety test. If a person is pulled over and asked to take a test when he or she is following all road laws and has not been drinking, the person may try to refuse a sobriety test due to lack of probable cause. While this may result in them being arrested regardless, some legal experts suggest a person is within their rights to refuse a test when no probable cause exists.
For offenders who have been caught multiple times driving under the influence or violating other alcohol laws, certain steps may be taken to schedule regular sobriety tests. This includes the use of embedded sobriety devices in cars, which link the ignition to a breathalyzer device and will prevent the car from starting if a sobriety test is failed. The cost of the installation is typically paid for by the offender.