Most of us are familiar with field sobriety tests for suspected drunk drivers. A DWI suspect may be asked to walk in a straight line or to stand and turn to indicate if he or she is intoxicated.
These tests are still widely used in Texas DWI cases to establish probable cause despite evidence that they are flawed and should not form any basis for a subsequent criminal conviction.
Although a positive breath or blood test recording of 0.08 blood/alcohol content (BAC) is required for a DWI conviction, a failed field sobriety test can consolidate a case against a suspected drunk driver. There are numerous reasons to refuse a field sobriety test and few good reasons for a driver to take one.
Police officers in Texas may use a bewildering variety of field sobriety tests. However, three are standardized by the National Highway Traffic Safety Administration (NHTSA). They are:
- One-leg stand
- Walk and turn
- Horizontal Gaze Nystagmus.
These tests are meant to find out if a driver’s coordination or his or her ability to follow instructions was impaired by drinking alcohol. The scientific validity of these tests is often questioned and there is evidence of widespread inaccuracy in testing.
The one-leg stand is a divided attention test. The one-leg stand test requires a suspect to divide his attention between the mental task of following oral instructions from the officer and the physical task of balancing on one foot for 30 seconds.
Critics of this test say it is intended to fail. It is problematic for a sober person to successfully perform this test under optimum conditions. To make matters worse, this test is typically administered on the side of a road, often late at night, when there are numerous distractions.
The walk and turn test entails walking in a perfectly straight line heel to toe, pivoting and repeating the movement. It can be a challenge in ideal circumstances. Although the NHTSA includes the walk-and-turn test in its list of approved field sobriety tests, the agency says it only has a 66 percent accuracy rate when administered correctly. Critics say this test is should not be used to establish probable cause for a drunk driving arrest.
The Horizontal Gaze Nystagmus test involves the police officer or trooper holding up an object such as pencil in front of the suspect’s face and asking the suspect to track it while the officer looks at their eye movements. The officer looks for evidence of involuntary jerking of the eyes called nystagmus which is commonly associated with intoxication.
The test is often improperly administered in Texas. Police officers may fail to take into consideration the natural nystagmus that occurs in people who are not drunk.
The three standardized tests are more reliable than some alternative field sobriety tests but they are not an accurate gauge of intoxication. Police routinely fail to take into account factors like weather conditions, a slippery or uneven surface and medical conditions of the suspect.
Few sobriety tests gauge alcohol content with any measure of reliability. They fail to take issues like age, gender and body type into account.
Despite the drawbacks in the procedures, flawed Texas field sobriety tests may be used to build a case against you. An officer may even argue you were drunk if you subsequently passed a blood or a breath test, if you failed a field sobriety test.
Motorists who refuse a field sobriety test face having their license suspended and being taken to jail where they will be given a blood test. Not only is this more reliable but it may benefit drivers who have consumed some alcohol because their BAC may have fallen.
Driving while intoxicated (DWI) is one of the most common offenses in Texas. Our Dallas criminal defense lawyers offer vigorous DWI defense.