Being arrested for DWI does not mean you will be convicted of DWI. An arrest means that a police officer believed there was probable cause to take you into custody. A conviction requires much more: the State must prove every element of the offense beyond a reasonable doubt.
Defending a DWI case therefore starts with examining exactly what happened—from the reason for the initial traffic stop through the officer’s observations, field sobriety testing, breath or blood testing, and arrest. Each piece of evidence should be evaluated independently and then considered as part of the case as a whole.
Importantly, a DWI defense does not always require proving that the driver was sober. The burden is on the State. The ultimate question is whether the prosecution can prove beyond a reasonable doubt that the person was intoxicated while operating a motor vehicle in a public place.
What Does the State Have to Prove?
Under Texas law, a person commits DWI if the person is intoxicated while operating a motor vehicle in a public place.
That gives the State three basic things to prove:
- The defendant was operating a motor vehicle;
- The vehicle was being operated in a public place; and
- The defendant was intoxicated at the time.
Texas law provides more than one way to establish intoxication. A person is legally intoxicated if he or she does not have the normal use of mental faculties because of alcohol, drugs, a controlled substance, or a combination of substances. A person is also intoxicated if he or she does not have the normal use of physical faculties for the same reasons. Finally, a person is legally intoxicated if he or she has an alcohol concentration of 0.08 or greater.
A prosecutor does not necessarily need a breath or blood result above 0.08 to prosecute a DWI. The State may instead attempt to prove that the driver had lost the normal use of his or her mental or physical faculties.
Likewise, a BAC above 0.08 does not eliminate every possible defense. The circumstances surrounding the collection and testing of the sample—and what the BAC was at the time of driving can become important issues.
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Criminal Defense
Reviewing the Traffic Stop
One of the first things a DWI attorney should examine is why the police officer stopped the vehicle.
The Fourth Amendment generally prohibits police from stopping a vehicle without a lawful justification. In a typical traffic stop, the officer must have reasonable suspicion that the driver committed a traffic violation or was otherwise engaged in criminal activity.
Unfortunately it’s often pretty easy for an officer to generate probable cause. Very few of us drive perfectly 100% of the time. If an officer suspects someone of being drunk, they may follow behind them until they violate some minor traffic law. This is called a “pretextual stop”. The office is using the minor traffic infraction as a pretext for the stop, but courts have allowed cops to do this. Sometimes they do make mistakes. If the traffic infraction is not supported by the dashcam or other evidence, it can be grounds for a motions to suppress.
What Happens if the Stop Was Illegal?
If a court determines that police unlawfully stopped or detained a driver, the defense may seek to suppress evidence obtained as a result of the unlawful detention.
That can be significant in a DWI case. The evidence obtained after the stop may include the officer’s observations, statements made by the driver, field sobriety tests, and potentially breath or blood evidence.
Most often, an unlawful stop will result in dismissal of the DWI, although this is not automatic.
The Officer’s Initial Observations
Once an officer begins speaking with a driver, the officer is typically looking for signs of intoxication.
DWI reports frequently mention observations such as:
- an odor of alcohol;
- bloodshot or glassy eyes;
- slurred speech;
- poor balance;
- fumbling with a driver’s license or insurance;
- admissions about drinking; and
- open containers inside the vehicle.
These observations can be evidence of intoxication, but they should not simply be accepted as conclusions.
Consider the odor of alcohol. An officer may truthfully testify that a driver smelled like alcohol. But the odor of an alcoholic beverage generally establishes that alcohol was present—it does not by itself establish how much alcohol the person consumed or whether the person was intoxicated.
The same type of analysis can apply to other observations. Bloodshot eyes can have causes unrelated to intoxication. A person may be nervous when confronted by a police officer. Balance can be affected by injuries, age, footwear, road conditions, or other physical limitations.
The defense should therefore consider both what the officer observed and whether those observations actually support the conclusions the officer drew from them.
Body Camera and Dash Camera Evidence
In many modern DWI cases, some of the most important evidence is the video.
Police reports are necessarily written from the officer’s perspective and often contain familiar descriptions: the driver had “slurred speech,” “bloodshot eyes,” was “swaying,” or appeared “unsteady.” Video provides an opportunity to test those descriptions against what actually happened. Officers are human, and they will often exaggerate things to make a person seem more intoxicated on paper than they actually were irl.
A DWI attorney reviewing body-camera and dash-camera footage may look at:
- the quality of the defendant’s driving;
- how the defendant gets out of the vehicle;
- whether the defendant walks normally;
- how clearly the defendant speaks;
- the defendant’s coordination;
- whether the defendant understands and follows instructions;
- the defendant’s interactions with officers;
- performance on field sobriety tests; and
- inconsistencies between the officer’s written report and the video.
Suppose an officer’s report states that a driver exhibited slurred speech and poor balance. If the body camera instead shows the driver having a coherent conversation, answering questions appropriately, retrieving requested documents, exiting the vehicle without difficulty, and walking normally, the video may become powerful defense evidence.
The opposite can also be true. Video can corroborate the officer’s account and make a case considerably more difficult to defend. Sometimes the most important witness in a DWI case is the camera.
Field Sobriety Tests
Standardized field sobriety tests are among the most familiar parts of a DWI investigation. They are designed to help an officer determine whether there is evidence consistent with intoxication.
The three standardized tests are the Horizontal Gaze Nystagmus, Walk-and-Turn, and One-Leg Stand.
The fact that someone exhibits one or more “clues” on these tests does not end the analysis. The tests are standardized, meaning the manner in which they are instructed, administered, and interpreted matters.
Horizontal Gaze Nystagmus
Horizontal Gaze Nystagmus, commonly called HGN, involves the officer observing the movement of a person’s eyes while the person’s eyes follow a stimulus, such as a pen or the officer’s finger.
The officer generally looks for six clues—three in each eye:
- lack of smooth pursuit;
- distinct and sustained nystagmus at maximum deviation; and
- onset of nystagmus before 45 degrees.
Unlike the other field sobriety tests, HGN is not primarily a test of a person’s balance or ability to follow complicated physical instructions.
A defense attorney should examine whether the officer administered the test according to the standardized procedure. The officer’s body camera can be useful for evaluating how the test was administered, although the camera will not necessarily provide a good enough view of the driver’s eyes to independently determine whether nystagmus was present.
Walk-and-Turn
The Walk-and-Turn is a divided-attention test. The person is generally instructed to stand in a particular position, take nine heel-to-toe steps along a line, execute a prescribed turn, and take nine heel-to-toe steps back.
Officers are trained to look for eight standardized clues, including beginning before the instructions are completed, stepping off the line, missing heel-to-toe, using arms for balance, stopping while walking, taking the wrong number of steps, making an improper turn, and being unable to maintain the instructional stance.
The number of clues is only part of the analysis. The defense should also examine the instructions the officer actually gave, whether the driver appeared to understand them, the surface on which the test was conducted, lighting, traffic, footwear, physical limitations, and other circumstances that may have affected performance.
There can also be an important difference between technically exhibiting a standardized “clue” and appearing obviously intoxicated to an ordinary person watching the video. A jury gets to see the actual performance.
One-Leg Stand
During the One-Leg Stand, the person is generally instructed to raise one foot approximately six inches from the ground, keep both legs straight, look at the raised foot, and count aloud until told to stop.
Officers generally look for four clues:
- swaying;
- using arms for balance;
- hopping; and
- putting the foot down.
Again, context matters. Age, injuries, physical conditions, footwear, surface conditions, weather, and the manner in which the instructions were given can all be relevant when evaluating the significance of the test.
BAC Testing: Breath and Blood
Many DWI cases include a breath or blood alcohol test. A result of 0.08 or greater can be powerful evidence because Texas law defines a person with an alcohol concentration at or above that level as intoxicated. But the number is not the only thing that matters.
Breath Testing
In a breath-test case, the defense should examine the circumstances under which the test was administered, the procedures followed by the operator, the operation and maintenance of the testing instrument, and the records associated with the test.
Also, if the State alleges a very high BAC but the video shows relatively normal driving, clear speech, good coordination, and comparatively strong performance on field sobriety tests, the apparent inconsistency may warrant closer examination.
Blood Testing
Blood evidence presents a different set of issues.
A DWI attorney may examine how the sample was obtained, who performed the blood draw, the collection materials and procedures, chain of custody, laboratory procedures, and the analytical results.
There is also an important timing issue. The offense is driving while intoxicated—not having a particular BAC when blood happens to be drawn later. Blood is frequently collected well after the traffic stop.
A blood result therefore has to be considered in relation to the time the defendant was actually operating the vehicle. Depending upon the facts, the State may attempt to use expert testimony and retrograde extrapolation to estimate an earlier alcohol concentration.
The farther the chemical test is removed from the time of driving, the more important the timeline can become.
Was the Defendant Actually “Operating” the Vehicle?
Not every DWI case begins with a police officer watching someone drive down the road.
Police sometimes encounter a person sleeping in a parked vehicle. Other cases arise from accidents where officers arrive after everyone has exited the vehicles. There may be multiple occupants and uncertainty about who was driving. Occasionally, a vehicle may be disabled or incapable of normal operation.
Texas’s DWI statute uses the term “operating” a motor vehicle, rather than simply “driving.” Where identity or operation is genuinely disputed, it can become a central issue in the defense.
Suppression of Evidence
A DWI attorney should also determine whether the State obtained its evidence lawfully.
Potential suppression issues can include:
- an unlawful traffic stop;
- an unlawfully prolonged detention;
- an arrest unsupported by probable cause;
- problems with a search warrant;
- an unlawful warrantless blood draw; or
- statements obtained in violation of constitutional protections.
A motion to suppress asks the judge to exclude evidence obtained in violation of applicable constitutional or statutory protections.. A successful motion to suppress does not automatically lead to dismissal, but in practical terms, that’s often what happens.
Next up: Resolving a case without trial. Plea Negotiations in DWI cases.