An FST (field sobriety test) and a BAC reading usually make up the majority of the arresting officer’s DUI investigation. Much like BAC testing, field sobriety tests are not infallible. With the right DUI attorney, You s can challenge the basis for their arrest.


Before the popularity of the ‘Breathalyzer’ (the most common breath blood alcohol content measuring tool), many officers of the law used field sobriety tests as a way to determine whether an individual was intoxicated while operating a motor vehicle. However, FSTs have lost favor since the advent of these machines. Yet, this does not mean that they are not frequently used by an arresting officer to investigate a person’s ability to drive safely, nor does this mean that they are foolproof.


The three most commonly used field sobriety tests are the ‘one-leg stand,’ the ‘walk-and-turn,’ and the ‘horizontal gaze nystagmus’ (HGN). According to two studies done by the NHSTA (National Highway Transportation Safety Administration) in the 1970s and the early 1980s, these three methods are the most accurate ways to prove intoxication. Despite this standardization, field sobriety test error rates remain at around 47%. The HGN test was only accurate 77% of the time; the ‘walk-and-turn’ was only accurate 68% of the time; and the ‘one-leg stand’ was only accurate about 65% of the time.


Very few police officers are correctly trained to read the results of these tests. In fact, studies have shown that officers are incorrect about 95% of the time when it comes to the HGN. An officer who administers this test correctly must have a great deal of knowledge and experience in order for the HGN to hold its own in court. It is a complex process, involving the officer placing a stimulus approximately 12 to 15 inches from the offender’s nose and slightly above their eye level. Then, once the stimulus is administered, the officer must determine whether or not both of the subject’s eyes ‘track’ in a constant manner and whether their pupils remain a constant size as well.


Various health-related factors could cause a person to fail any one of the three field sobriety tests. The first being problems with the inner ear (which regulates balance). A perfectly sober individual who has inner ear issues would be unable to perform to an officer’s satisfaction. Likewise, many individuals over the age of 65 have problems with these tests due to arthritis or orthopedic issues. If you failed a FST and fit one of these distinctions, contact a DUI attorney. Bay Area residents no longer have to live in fear of unlawful arrest, fines, or jail time due to DUIs.


Given the difficulty of administering this test correctly it’s highly advisable to get help from a DUI attorney. Bay Area residents choose the skilled legal team at Summit Defense for all their DUI-related charges.