Articles Posted in Criminal Defense

In our last blog entry , we completed analysis of the criminal defense of the Horizontal Gaze Nystagmus (HGN) test.

The next major test a New Braunfels DWI lawyer must overcome is the Walk and Turn (WAT), where the driver is instructed to walk heel-to-toe while counting in a loud voice with each step. In this test, the driver will walk nine (9) steps , turn around, and walk back nine (9) steps. All steps are heel-to-toe. In this test, the arresting officer wants to highlight the inability of the driver to maintain his balance and / or a failure to properly follow instructions.

According to the National Highway Traffic Safety Administration (NHTSA) Manual, there are eight (8) potential clues. If the driver fails on at least 2 of the clues, then the theory goes that the Blood Alcohol Level (BAC) is over the legal limit of .10. During the test, the driver may make mistakes such as stepping off the line. The Manual states the person has failed the test if he steps off the line more than 3x. Any evidence that the driver is about to fall and injure himself is also enough to demonstrate a failure on the WAT.

In our last blog entry, we discussed some ways to attack the validity of the Horizontal Gaze Nystagmus (HGN) test.

During a jury trial, the jury will review the video, but it is highly unlikely that they can pick up the subtle bounce or nystagmus of the eye from the video. They are essentially relying on the officer’s testimony that he witnessed clues of intoxication related to nystagmus. A jury will be extremely doubtful of the officer’s observations, if a Bexar County DWI attorney can demonstrate that the officer has written reports with mistakes, that his testimony differs from the video, and that he did not perform the HGN test according to NHSTA specifications.

An especially strong tactic is when the officer claims that the driver was swaying and unable to stand steadily. Well, the inevitable question when an officer testifies like this, is how on earth he could possibly estimate a 45 degree angle for onset of nystagmus if the driver is swaying? The officer will either claim he could detect the nystagmus before a 45 degree angle was reached on a person moving back and forth or that somehow the driver was able to stand still throughout the HGN field sobriety test. The officer will inevitably contradict himself and the jury will cast doubt on his credibility. Any swaying during the HGN will ultimately render the HGN test invalid. If the officer contends the driver was swaying but then remained still during the HGN test, the jury will question whether in fact the driver was intoxicated if he was able to stay still during the entire administration of the HGN test.

In our last blog entry, we discussed the basics of the Bexar County HGN Sobriety Field Test . In this blog entry, we will now discuss some inherent weaknesses of the HGN test as a test of intoxication. A seasoned San Antonio criminal defense lawyer will be able to employ certain techniques to demonstrate to a jury the inherent weaknesses of the HGN test as a test of intoxication.

There are certain time periods in the NHSTA manual regarding the administration of the HGN test that must be followed. Specifically, there is a certain length of time that must be met in the “smooth pursuit” test as the officer moves the flashlight in front of the driver’s eyes. When the officer directs the flashlight to the side, that light must be held at maximum deviation for a specified time. A well trained Bexar County or Wilson County DWI lawyer will scrutinize the DWI video and make sure the tests are done within the proper time parameters according the NHSTA standards.


We know that under the HGN test, there can be up to 6 clues of intoxication – three (3) clues in each eye. According to the NHSTA manual, when four (4) or more clues are present whether it’s through lack of smooth pursuit, a distinct nystagmus, and onset of nystagmus before a 45 degree angle, the HGN is accurate a little over 75% of the time. This 75% rate means that inherently the HGN test has a 25% rate of error when it comes to predicting intoxication. A 25% rate of error is certainly not a low enough rate of error in any juror’s mind to demonstrate legal intoxication beyond a reasonable doubt.

In our last blog entry on general issues regarding Texas DWI SFSTs , we touched on the three (3) major field sobriety tests. Today, we will discuss the first major SFST. In Bexar County and surrounding Wilson and Atascosa County, a seasoned San Antonio DWI lawyer must deal with challenging the first major DWI Field Sobriety Test (SFST): Horizontal Gaze Nystagmus (HGN). During this SFST, an arresting officer will employ a flashlight and position the flashlight in front of a driver’s eyes.

The flashlight is moved back and forth to test whether a driver’s eyes will involuntarily jerk or bounce when the eye rotates far to the left or right. Physiologists call the bounce a nystagmus and the jerk of the eyes will usually occur to the left or right, making it a horizontal nystagmus as opposed to a vertical nystagmus.


According to the National Highway Traffic Safety Administration (NHTSA) Manual, there are three clues of intoxication related to the HGN test for each eye for a total of six (6) possible clues. The three basic HGN clues are a lack of smooth pursuit by the eye, a distinct jerking or nystagmus, and a jerking of the eye before it reaches a forty-five (45) degree angle.

There are basic Standard Field Sobriety Tests (SFSTs) prescribed by the National Highway Traffic Safety Administration (NHTSA): the Horizontal Gaze Nystagmus (HGN), the Walk and Turn (WAT), and the One-Leg Stand (OLS). A San Antonio DWI lawyer will have a strong grasp of how Texas law enforcement is supposed to administer the tests and the specific vulnerable areas in each test that are open for challenge.

There are some basic general concepts regarding SFSTs. The SFSTs are constructed in such a manner so that the participant WILL fail them. Within a short time after the driver has exited the vehicle, law enforcement has already decided that the driver is intoxicated and only seeks SFSTs to convince a jury on video. The SFSTs must be administered by qualified law enforcement. A San Antonio criminal defense lawyer will obtain proof of certification from the Texas Commission of Law Enforcement Officer Standards and Education (TCLEOSE) . Moreover, active certification only lasts 2 years before the officer requires recertification. Therefore, there is the very real possibility that an officer is not properly certified to administer the SFSTs.


In our last blog entry, we discussed how San Antonio law enforcement will use distracting questions that are not DWI standard tests in order to see if the driver can perform different tasks at once. This “unusual” questions technique continues while the officer gets ready to administer the SFSTs. The officer will ask the driver to move to a different position before each SFST to demonstrate on video if the driver sways and stumbles while moving to a different area of the roadway.

In our last blog entry on phases of the Texas DWI Stop , we discussed Phase 1 (Vehicle in Motion) and Phase 2 (Personal Contact). When we left off, we discussed how a police officer will try to divide the attention of driver by asking distracting questions to see if the driver can handle “divided attention” tasks.

Another tactic which is not used by the San Antonio Police that much is to ask unusual questions. These are not standard tests – for example, a police officer might ask the driver to recite the alphabet from “F” to “Q” instead of the normal ABCs. Another unusual question is counting backwards from 79 to 60. The bottom line is than any jury member, when given such questions, whether or not they are intoxicated , would tend to get confused.

The “unusual question” test is not a Standard Field Sobriety Test (SFST) and a San Antonio DWI defense lawyer will use trial motions to have the court exclude such test. If these tests are not excluded, the officer will still be forced to admit under the National Highway Traffic Safety Administration (NHTSA) Manual, an inability to perform or answer such unusual tests / questions does not constitute probable cause for intoxication.

In the majority of DWI cases in San Antonio, the Bexar County District Attorney usually has a video demonstrating the alleged offender performing a series of field sobriety tests with a breathalyzer score over the legal limit of .08.

Given these elements, you may feel that a San Antonio DWI lawyer has very little chance of obtaining acquittal. This blog entry will cover some aspects of how a DWI defense attorney can reveal the shortcomings of both the Standard Field Sobriety Tests (SFSTs) and readings from the Intoxilyzer-5000 breathalyzer.

Officers in the San Antonio Police Department receive their training on how to conduct DWI arrests from the National Highway Traffic Safety Administration (NHTSA)manual. This manual lists several important standards that must be met in order for officer to properly detect intoxicated drivers and properly conduct the SFSTs.

In the seminal case Berghuis versus Warden , the United States Supreme Court issued major changes affecting the invocation of Miranda rights. Specifically, the Supreme court led by Justice Kennedy ruled that a defendant must clearly invoke their right to remain silent ie. their Fifth Amendment right against self-incrimination. In the past, an accused could stay silent and this was enough to invoke the right to remain silent. No more…

Under the facts of Berghuis, the Court ruled that the defendant had to explicitly and unequivocally state to the arresting officers that he was invoking his right to remain silent. By NOT expressly invoking his right to remain silent, in effect the Supreme Court ruled that the accused was WAIVING his right to remain silent.

According to the facts, an accused Michigan man sat for three (3) hours in silence while officers interrogated him and then confessed to a murder. The question was whether the defendant’s silence constituted an invocation of the right to remain silent, such that the confession was inadmissible. The Supreme Court ruled that under such circumstances, it would have been impossible for the officers to have determined whether the accused was invoking his Miranda rights. Since the Michigan man seemed to indicate his understanding of his right to remain silent and the officers did not coerce his confession, then in effect the accused waived his right to remain silent by making statements during the interrogation.

As I have handled more San Antonio criminal defense cases, I have come to the startling revelation that many of my clients would not find themselves in their current situation if they applied some basic rules when dealing with the police. If you are willing to remember some key points when dealing with the police, then you stand a far greater chance of either being released with a simple citation or being acquitted of all charges if you are actually arrested.

You can prevent a traffic stop from turning into a Bexar County misdemeanor or a misdemeanor from turning into a full blown San Antonio felony charge.

People have this naive idea that the police are willing to work with them, and if they simply explain the situation, the police will empathize and release them Wrong! The police are not your friends – think of them as the agents of the District Attorney’s office. The job of the police is to build a case against you. Even the purely innocent must be wary of any statements made to the police. What if the police claim you stated something you didn’t or they misinterpret your statements? Can you imagine a jury having to determine between a criminal defendant and a police officer as to who is telling the truth ? Who are they more likely to favor ? It is a no win situation and a lesson you should learn now as opposed to later.

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