Being charged with impaired driving is a serious criminal offense in Texas. Prosecutors are serious about punishing those convicted of driving intoxicated, whether it is due to alcohol or drug use, and defendants can expect a stern position from the prosecuting attorney. However, they still must prove beyond a reasonable doubt that the defendant was indeed impaired according to state standards. Those standards are set at .08 blood alcohol concentration for alcohol, but for other substances the standard is practically zero tolerance. This is why it is important to keep officers honest regarding arrest protocol when being charged with DWI.
Improper sobriety field test
One of the primary defenses in a drunk driving case is improper administration of a field sobriety test. Not all officers are trained in the procedure, but they will conduct them anyway if inebriation is suspected. This can be a point of contention because it could establish that they did not have reasonable suspicion to investigate for probable cause. This can also include unlawful search and seizure for those accused of driving under the influence of drugs or substances other than alcohol.
Defective testing devices
Results of a field sobriety test are not the only element of a DWI charge that can be contested. The actual equipment used in an alcohol case must be calibrated and inspected on a regular basis. Evidence can be presented from other cases where the same machine has been used and presented problems with accuracy, which can establish reasonable doubt if it has not been repaired since that time. Blood tests administered without an authorized warrant can be suppressed as well in DWI charges not involving alcohol.
This is not a complete list of potential defenses in a DWI case where police officers acted in a questionable fashion when attempting to find probable cause. Reasonable suspicion must always be found and documented before an officer can proceed with a traffic stop. Although prosecutors do not want to admit it, a conviction is not always automatic even when they have a BAC result against a defendant that is beyond the minimum.