To be charged with Driving While Intoxicated (DWI), a law enforcement official must build a case against you by proving you operated a motor vehicle while intoxicated. You are intoxicated while driving in Texas when your blood alcohol concentration (BAC) level is at or over .08%. To determine your intoxication level during a traffic stop, a police officer who suspects you are drunk driving, will ask you to participate in field sobriety testing.
If You Drive in Texas, You Have Already Consented to Field Sobriety Testing
Texas is an implied consent state. This means that by driving on Texas roads you have already consented to DWI field sobriety testing when asked to participate in tests by a law enforcement official. You can nonetheless respectfully decline to be tested, remain silent, and request the presence of a DWI defense attorney.
Standard Field Sobriety Testing
The Standard Field Sobriety Test (SFST) is a three-part test performed by law enforcement officials during a traffic stop to determine whether or not a driver is operating a vehicle over the legal BAC level. This test usually precedes the Breathalyzer test. Failing the SFST and breathalyzer test may lead the police officer to request a blood test from you to determine your BAC level or support a probable cause finding to make the DWI arrest.
SFST Tests are Admissible as Evidence in Court
Police officers record a drunk driving suspect’s performance on the field sobriety tests to use as evidence against him or her in a DWI case. The three tests administered during SFST testing are the horizontal gaze nystagmus (HGN), the walk and turn (WAT), and the one leg stand (OLS) tests.
HGN measures the involuntary movement of eyes. Generally all eyes move involuntarily when they gaze to the side. When a person is intoxicated, the involuntary movements are more pronounced. Police officers look for three indicators of impairment for each eye: inability to smoothly follow a moving object; distinct eye jerking when eye is at maximum deviation, and eye jerking within 45 degrees of center. WAT measures balance by dividing the attention of the drunk driving suspect. The suspect takes nine steps heel to toe along a straight line, turns on one foot, and then repeats steps in the same manner in the opposite direction. OLS requires drunk driving suspects to stand on one leg for 30 seconds with one foot about six inches off the ground, while counting. Like the WAT, the OLS is a divided attention test measuring balance and coordination.
Impairment in all three tests is measured by evaluating the drunk driving suspect’s inability to complete the test or method used by the drunk driving suspect to compete the tests. The drunk driving suspects who fail the field sobriety tests are next administered a breathalyzer test to determine their BAC level before an arrest is made.
Arrested for DWI?
The law offices of Kimberly Griffin Tucker is a full service law firm focusing on DWI/DUI criminal defense. Serving the cities of Plano and Dallas, Texas throughout Denton, Collins and Dallas counties, we are committed to helping you resolve your DWI case as quickly as possible. Call (214) 445-6336 or email us to schedule your free DWI consultation without delay.