Defending a DWI in Texas

Top Defenses to Driving While Intoxicated Charges in Texas


As in all criminal cases, a person charged with Driving While Intoxicated (DWI) is presumed innocent. The State has the burden to prove the defendant guilty beyond a reasonable doubt. The person charged must be acquitted if the State fails to meet its burden. An effective defense will protect the defendant’s presumption of innocence and prevent the State from meeting its burden.

What the State Must Prove?

An effective DWI defense strategy will attack the prosecution’s case on multiple fronts, with the goal of preserving the defendant’s presumption of innocence. A person may be convicted only when the State offers admissible evidence to rebut the presumption of the defendant’s innocence. To be found guilty of DWI, the State must convince a jury that the

(1) defendant operated a motor vehicle,

(2) in a public place while either

(3) under the influence of intoxicating liquor or with a .08 or greater blood alcohol content (BAC).

A defendant must be acquitted if the State cannot, or fails to, prove the defendant guilty of each of the three elements of DWI. A person may not be tried for the crime again if they were acquitted after trial. In other words, the State does not get a second bite at the apple.



The defense has ample opportunity to attack the State’s case both pre-trial and during trial. During the pre-trial stage, the defense can contest the reason the officer stopped you while driving. This contest is called a Motion to Suppress Evidence. At a Motion to Suppress Evidence, the State has the burden to prove the officer did not violate the driver’s constitutional protections against unreasonable searches and seizures. Thus, the State must prove the officer had a specific and articulable reason or reasons to stop the car and order the driver out. The State must also prove that any statements the driver made did not violate the Miranda warnings and were made knowingly and voluntarily without being coerced. A judge will order every piece evidence, such as observations of the police, video recording of the stop and booking, portable breath test (PBT) results, field sobriety tests (FST), statements made by the driver, and breathalyzer tests (BT) or refusal suppressed if the police violated the driver’s constitutional rights. The State is prohibited from using suppressed evidence at trial. This means the State will not have any evidence to produce at trial, resulting in a dismissal of the charges.


The defense can also attack the State’s scientific evidence as well. To be admissible, evidence such as Horizontal Gaze Nystagmus (HGN) PBT, BT, and blood tests require the State to call an expert witness to testify. The defense attacks the evidence on the basis that the testing is scientifically unreliable and should not be admitted in evidence at trial. The defense also attacks the expert personally, arguing that the witness lacks sufficient knowledge, training, and experience to offer a scientific opinion at trial. These same attacks should also be made during the trial; however it is beneficial to the defendant to attack pre-trial. A pre-trial contest of the scientific evidence, even if unsuccessful, gives the defense a great advantage to learn about the evidence in advance of trial, providing an opportunity to fashion a winning defense.

The State’s scientific evidence may be unreliable, and therefore inadmissible, for three reasons.

(1) The test may be scientifically unreliable. Defendants have successfully argued that HGN and PBT tests are scientifically unreliable and should be not admitted at trial.

(2) Errors made by the person administering and interpreting the tests are frequently a successful avenue of attack. For instance, a judge may find the HGN test admissible because it is scientifically reliable but the person administering the test failed to follow the correct procedure or mistakenly interpreted the results.

(3) Any machines used such as the PBT or BT may yield a damning result but may have been incorrectly calibrated.  The use of defense experts is critical here. An expert retained by the defense can help question the reliability of the HGN, PBT, BT, and blood tests pre-trial. Also, the defense expert can testify for the defense at trial to create doubt that the evidence the State offered lacks scientific reliability and the State’s expert witness lacks credibility.  The aim is to give the jury a reason to disregard or downplay the significance of the State’s scientific evidence. Additionally, a defense expert might be able to testify that the driver’s BAC was lower at the time the officer stopped the driver, casting doubt on the accuracy of the BT reading.


The police officer’s testimony is grounds for attack as well. A trial in which an officer does not testify well or hold up under cross-examination by the defense often results in an acquittal for the defendant. Police officers, for as much good as they do, are human. The accuracy of the officer’s memory, testimony inconsistent with what was written in the police report, and any bias the officer may have are all methods used to attack the officer’s credibility.  Exploiting these issues at trial may help secure an acquittal, because the jury might not be convinced by an officer’s testimony that is biased or an officer who testifies to observations made which were not in the police report.

The arresting officer’s observations during arrest must be attacked. The officer will testify as to observations of smell of alcohol, bloodshot and watery eyes, slurred speech, poor driving and poor performance on the FSTs. On direct examination, the evidence will sound overwhelming. A good cross examination will open substantial holes in the officer’s testimony. This is where the best defense lies. The officer may have been trained in the academy to administer FSTs with a particular method but may not have followed the training and administered the FSTs incorrectly. The manner in which the FSTs were administered might have been unfair. For instance, the cruiser’s lights might have been in the driver’s eyes, the road might have been uneven, the officer may not have explained the test well or accurately, or the driver may have had an injury preventing successful completion of the tests. The driver might have performed well on the tests by following directions but was not perfect according to the officer. The results on FSTs, to a large extent, are subjective.  A good thorough cross examination will demonstrate to a jury that the FSTs should not be given as much weight as the State argues.

A winning defense strategy in a DWI case will explore many areas. Since every case is different, an experienced DWI attorney will explore all of the avenues discussed above in defending a case.

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