Carl David Ceder - Attorney and Counselor at Law

Texas DWI Breath Test Defense Attorney

When you an individual is arrested on suspicion for a charge of Driving While Intoxicated (DWI) anywhere in the greater Dallas-Fort Worth region, the arresting police officer will likely ask for the submission to obtain a chemical test, either via by breath or blood. If you believe you may be under suspicion for a DWI in Texas (or have already been arrested for a DWI), it is crucial to seek the assistance and counsel from an aggressive, trained, and skilled a DWI Defense Attorney in order to help you understand the nature of your situation, what possible options are available, and which defense may be able to be launched into effect to help mount a successful defense.

There are two different types of chemical tests that can be used in the State of Texas to help support a DWI charge against you to be used as evidence, the easiest of which for the police to obtain is via a consensual breath test (the other is by the taking of a specimen of blood). Many people voluntarily submit to a breath test, often because they genuinely feel they are not intoxicated when arrested. As well, many people operate on the mistaken assumption that they have to voluntary consent to giving a chemical specimen upon request. This concept and belief in people, in my opinion, is due in large part to the propaganda of the “No Refusal” weekend, whereby people feel they have no choice but to do whatever is asked when they are questioned on if they will agree to give a sample. If you should refuse, a blood search may be obtained (regardless of whether it is a No Refusal Weekend or not), which is not a law passed by the Texas legislature, but is also a simple local policy among police departments that they will get a search warrant should a person refuse. To read about the rationale and police associated with “No-Refusal Weekends” – please read more: HERE.

A great number of individuals agree to voluntary give a specimen of their breath, sometimes because they genuinely feel they are not intoxicated and feel they have nothing to hide by giving a sample of their breath. Among these people, many are later shocked at the results given and baffled by how high a reading the machine said their BAC was and therefore vehemently disagree with the results. While the evidence may seem relatively certain at the time, it is VERY important to remember that a variety of factors can lead to an inaccurate reading. Regardless of your situation, it is imperative that you retain the services of a skilled criminal defense attorney who has researched and is familiar with the machine Texas uses for breath tests in DWI cases, in order to help sort through the details of your arrest and/or why the breath test machine may have given a false-positive result. Texas just phased out the older Intoxilyzer 5000 machines in favor of the newer model, and now most departments are using the Intoxilyzer 9000. The Intoxilyzer 9000, it should be noted, has just as many flaws as the previous machine used by the police in Texas, if not more so.

Portable Breath Tests (PBT’s) Devices

Often a police officer will request for a person under suspicion for a charge of DWI to blow into a little device after performing the roadside tests. Many people mistakenly believe this is the actual breath test used to gain a chemical measurement, but this is not the case. The PBT is simply a confirmatory device used to determine if a person has consumed alcohol. The arresting officer will perform a breathalyzer test with a handheld device on the scene or may test you after you have been arrested (this is referred to as a “PBT” – and the results are not admissible in a court of law). By law, you can refuse this handheld breathalyzer test – it is merely a tool used by the investigating officer to aid in his decision to arrest; however, the arresting officer may not tell you about your rights before the test. It will a number of an estimated BAC, but this result is not admissible in a trial later because of how inaccurate and imprecise the result usually is.

You are never required to offer, nor should you voluntarily submit to the taking of a breath sample on a PBT device when on the side of the road about to be placed under arrest for DWI. This usually is only done to help give the investigating police officer additional probable cause to be used to justify making an arrest. Before asking for a specimen to be given on the PBT device, a police officer is not required to allow you to contact an attorney before you decide to refuse or take the breath test (which is also true once you are asked again to give a voluntary specimen on the Intoxilyzer 5000 or 9000 later at the jail).

Once arrested and at the jail, the arresting officer has to read what is termed the “DIC” statutory warnings, which is a very convoluted way of asking a person if they want to consent to, or will refuse, to give a voluntary specimen of their breath or blood. You will be read, after being placed under arrest, what is called the “DIC-24 Statutory Warnings” – which will basically ask if you will consent, or refuse, to the taking of a chemical specimen – which if consent is given, is usually on the Intoxilyzer 5000, and now more frequently is conducted on the Intoxilyzer 9000.

However, if you refuse to the voluntary taking of a chemical test after you have been arrested for DWI, it likely will result in losing your driver’s license for a certain length of time. If you do refuse to the taking of a chemical specimen, the investigating officer MUST obtain a legal and valid search warrant before they can draw your blood. Often there is not a Judge available to get the search warrant signed, or they may not go through with this simply because the length of time the entire process takes. Either way, you should refuse to voluntarily give consent to the taking of any and all tests, because they are simply going to be utilized against you in a court later on. If the investigating officer does get a blood search warrant, we can attack it later in court. If this does occur – simply voice your position that you are not agreeing for a chemical to be taken, but do not argue, fight, or act uncooperative in the event a blood search warrant is obtained. 

Implied Consent

As outlined in Section 724.016 of the Texas Transportation Code, any person arrested for DWI is required by law to submit to giving a voluntary chemical specimen. That being said – a person is not absolutely required to do so, as it is just a way, in my opinion, to try and induce individuals into giving a sample of their breath.

While it should be noted that while one should refuse to comply with giving a voluntary specimen of their breath (or blood), it is also important to understand that this refusal will come with some consequence. If a person does refuse to give a breath or blood test upon request, their driving license privilege will be suspended for a period of 180 days for a 1st-time DWI arrest (the license suspension lengths usually are longer in duration if it is a DWI-subsequent offense).

A variety of studies and data has consistently shown how the breath test machine will very often yield to results given which are false-positives, It is widely known within the DWI Defense community how inaccurate and unreliable giving a sample of your breath (to measure your BAC – which is your blood-alcohol level, not your “breath alcohol” level”). In fact, a calculation and a conversion have to be conducted to convert the BrAC measurement given on a breath test machine to render results that can be possibly correlated into what a person’s “blood-alcohol” concentration may be. However, there is a difference between being precise, accurate, and reliable. The breath testing machines as used by Texas has not ever shown to reliably deliver results that would be characterized as such. Both machines are similarly deficient and are simply very raw and imprecise tools for measuring what should be a very exact number – a person’s blood-alcohol content (BAC) level may be after an individual is arrested and accused of DWI. Machines and equipment are never perfect; as they are prone to fault, error, and miscalculation. This is especially true as it applies to the Intoxilyzer 9000 (and previously with the Intoxilyzer 5000).

Most attorneys, including many who agree to represent individuals arrested for charges of DWI, simply do not understand the science and underlying method for how the machine works, which would make it difficult, if not impossible, for one to be able to determine and detect any possible inaccuracies in breath test device utilized, and when analyzing the result.

Many things can go wrong when an individual agrees to give a specimen of breath, which both can yield to various ways for false-positive results occurring. Various studies have indicated the many different ways the breath test machines used in Texas having a very high propensity for error yielding false-positive and questionable results. Many factors can lead to problems with analyzing whatever measurement is given with a breath test, all of which lead to further uncertainty on just how high the propensity for error actually is.

The list below is a list of possible ways which can lead to inaccurate and imprecise breath test results from either breath test machine used in Texas. Shockingly enough, what is written here does not even come close to detailing everything, and the list below is actually NOT exhaustive of all issues that the machines could make. This seems to be almost unconstitutional or unAmerican in many respects, especially when considering how the results gathered and ultimately are used to determine a very critical measurement (a person’s BAC level after a DWI arrest). The resulting figure can have a serious and negative effect in a very real and detrimental way for people, compromising their liberty and freedom, their future, possibly their employment and ability to have a livelihood, etc. Again, these are just a few of the reasons which can lead to a false-positive result with breath testing machines used in Texas.

Some of these factors include:

  • Not properly maintaining or calibrated the machine as often as necessary (improper calibration), and/or dirty or not properly maintained equipment;
  • There is always the possibility for routine machine error or even mistakes made by the operator of the machine, possible interferents of chemical substances in the person’s system or in the room that can affect the results can potentially compromise a sample collected. The breath test machines used in Texas (this is true with either the Intoxilyzer 9000 and/or the Intoxilyzer 5000) often do not have the ability to detect for the possible presence of other substances which cannot be accounted for (such as diethyl ether). If certain substances and chemicals are present (perhaps in the room from a previous person who gave a breath test, or maybe on the person’s clothing, etc.) it can lead to the breath test machines to mistakenly pick up other substances which act as interferents, because they do not have the ability to make the distinction from alcohol or ethanol. Certain conditions can exist, possibly due to an individual’s occupation and possible exposure to certain chemicals, which the breath testing device may misread as ethanol when it is not (simply because it is a machine, and cannot tell where substances of like chemical composition are coming from);
  • There can also be mistakes made by the Intoxilyzer operator when administering the test, often the machine is not capable of detecting and flagging other substances in a person’s mouth or in their system, that the machine may detect and read as alcohol when it is not;
  • Even simple things such as what is termed Radio Frequency Interference (RFI) can occur which can compromise the sample collected. The company that manufactures the breath test machines, CMI Inc. of Owensboro, KY, specifically states how Radio Frequency Interference can affect how the machine operates, and thus – everyone in the Intoxilyzer room should turn off all electronic devices (including police walkie-talkies, and cell phones, etc.);
  • An individual’s specific rate of metabolism, which can affect the way ethanol (alcohol) is absorbed and eliminated within their system;
  • Studies and experts have shown that varying breathing patterns and the pressure of the breath when giving a specimen can lead to possibly as much as a 30% or more. Most operators know this and therefore can manipulate the samples by encouraging subjects to blow commensurate with the level of the previous sample. Dr. Micheal Hlastala, Professor of Physiology, Biophysics, and Medicine at the University of Washington, once concluded the following (please see the December 2002 study “Breathing-Related Limitations to the Alcohol Breath Test”):

“By far, the most overlooked error in breath testing for alcohol is the pattern of breathing….The concentration of alcohol changes considerably during the breath…The first part of the breath, after discarding the dead space, has an alcohol concentration much lower than the equivalent BAC. Whereas, the last part of the breath has an alcohol concentration that is much higher than the equivalent BAC. The last part of the breath can be over 50% above the alcohol level….Thus, a breath tester reading of 0.14% taken from the last part of the breath may indicate that the blood level is only 0.09%.”

  • Unqualified or untrained police officers administering a breath test (who may not have completed the required proficiency courses to allow them to operate the machine as a qualified Intoxilyzer Operator – and even if they have done so, I have reviewed countless cases where a person who has completed the certification still makes very blatant and clear errors when obtaining a breath test result;
  • A person’s body’s temperature (if an individual has a fever or has a body temperature when giving the breath test higher than usual, it will lead to a result also not correct and higher than what the true BAC actually is;
  • Issues such as these can include a person who is taking certain prescription medicine, dietary supplement, or has a physical condition (such as “GERD” or acid reflux disease), has breathing problems such as asthma, experiences chronic heartburn, etc. can all compromise the sample collected if not taken into account.

The items identified above, believe it or not, is just the tip of the iceberg with how many things can go wrong with a breath test. The main point, regardless of all else, is that it is NOT an accurate measurement of a person’s BAC level, but merely provides a possible range of possibilities for where they may be have been at a certain period of time.


A driver that fails a breath test and is subsequently charged with a DWI offense will face significant and often severe civil and criminal penalties often with just being arrested, but also if later convicted of the charge at court. Some of these penalties and punishments that can occur are:

  • Confinement in jail or prison (the penalty range increased with DWI offenses based on an individual’s prior record if they have been previously conviction of a DWI);
  • Steep fines;
  • DPS Surcharges;
  • Suspension of the license to drive, and thus having to obtain an occupational driver’s license;
  • DPS reinstatement fees when if a driver’s license is suspended to regain the legal right to again be able to drive without the “essential needs” license;
  • Probation;
  • Court Costs;
  • A possible permanent criminal record if convicted;
  • The requirement for the installation of an ignition interlock device as a condition of bond or as a condition of probation, often for lengthy periods of time;
  • Community service hours;
  • Mandatory attendance at certain approved alcohol or drug education classes and programs;
  • Probation Fees (and many other possible financial repercussions exist when arrested for a DWI offense in Texas).

Intoxilyzer 9000

The State of Texas is currently on the verge of replacing the Intoxilyzer 5000 EN and transitioning to the Intoxilyzer 9000 for breath alcohol testing. According to a representative of the manufacturer of the device, it is meant to work by infrared light absorption of alcohol detected in a person’s breathing.

The device works in a way that it subtracts the amount of light absorbed from a person’s breath sample, and compares the amount with the amount of light initially introduced by the device into its testing chamber. After this whole process, it prints the difference as a test result. Summarily, the Intoxilyzer 9000 works by looking for the presence (if any), and amount of alcohol in a breath sample.

It uses infrared light technology to both identify and quantify ethyl alcohol in a breath sample. The trick here is that ethyl alcohol uniquely absorbs infrared light. As the pattern on the device is used to identify alcohol, it also shows the amount of absorption used to quantify alcohol in a breath sample. The final result from the Intoxilyzer 9000 is printed as an analytical result in grams of alcohol and 210 liters of breath as stated by Texas law.


Research and studies have shown that the main difference between the Intoxilyzer 5000 and the Intoxilyzer 9000 is the presence of what is called ethanol “fingerprint” in the Intoxilyzer 9000 version. In other words, the machine itself is more suspect to the interference of non-specific alcohol content. In situations where the Intoxilyzer 5000 measured the carbon-hydrogen (C-H) bond vibrations in the 3-micron region of ethanol’s molecular fingerprint, the Intoxilyzer 9000 measures the carbon-oxygen (C-O) vibration in the 8– 9-micron region. The flaw in this design is that other molecules are commonly found in the human body with this same C-O stretching. Specifically, other organic particles can potentially contaminate breathe test samples. Some of these organic substances include certain ethers, that are similar alcohol on a molecular level because each contains both the methyl group and carbon-oxygen bonds in their molecular structures,

The Department of Public Safety in Texas (DPS) has taken the stance of refusing to allow for the review of the histograms for the Intoxilyzer 9000. he Intoxilyzer 9000 automatically has the capability and does actually print off a physical copy of the histogram, which can render relevant information that should show or demonstrate the person’s breath flow, breath volume, and the length and duration of the blow into the machine. The histogram is important for a variety of reasons because it produces a graphical representation of data that is relevant to determine crucial and vital information, such as whether there was sufficient “slope” for the sample (the two results given have to be within a certain range of each sample given). It may show the presence of interferences and/or can help determine if a test was contaminated by mouth alcohol. Other states, such as Georgia and Colorado, provide a variation of the histogram, which can help to ascertain pertinent and relevant information to help with proving the validity of a result given. Why has Texas taken the position to do otherwise if the machine was not subject to error and false-positive results?

DPS in Texas refused to produce any variation of a version of a histogram of a breath test result, even though it would come at no imposition to them if they chose to do so because it is readily available. This is confusing and leads to further speculation of how imprecise the Intoxilyzer 9000 is (perhaps even more so than the 5000) because every breath test result given produces a print out of the histogram, but for some reason Texas has chosen as a policy to not store or save the histogram, nor any variation of the data it interprets. DPS has clearly demonstrated, that at the very least it does not believe the citizens of Texas deserve the same protection afforded to those who live in other states, and/or if not – it is an obvious indicator that they do not want to produce the histogram results because of how often it would be questioned and attacked later in court by DWI Defense Attorneys.

Another problem exists based on how there are less “filter wheels” in the Intoxilyzer 9000 than there were in the Intoxilyzer 5000. While the original Intoxilyzer 5000 uses a tungsten filament light source that provided continuous IR and visible radiation, theIntoxilyzer 9000 on the other hand, uses a grey body infrared light that pulses the energy through the sample chamber to a stationary detector that contains only four filters, each of them having a specific wavelength of IR radiation with lack of a zero set. Where the Intoxilyzer 5000 had a blank or a zero filter in the wheel, the Intoxilyzer 9000 does not have a detector for a real zero. Instead, the machine assumes or is programmed to read zero if the filters do not detect other samples besides alcohol.


Although DPS had a very prolonged and lengthy delay before the implementation of Intoxilyzer 9000, as it just now seems to be in more full use, but one has to question the reason for why the length of time for the delay when finally putting in place the testing program for the Intoxilyzer 9000, which was originally scheduled in Texas for use as far back as the summer of 2015. For years the proposition lingered that at some point it would be put into use replacing the old machine that was first created and put into use in the early 1980s. Much is already known from information gathered from other states have had it in use for a longer period of time, and as such, based on this much is already known from their use which indicates and illustrates the many deficiencies of the Intoxilyzer 9000. An experienced DWI lawyer can educate the court and a jury about the deficiencies of the machine’s accuracy and reliability based on what is already known – but I suspect that as time goes by, other information will come to light which demonstrates it’s flawed nature.

In a similar fashion, DPS has chosen not to partake in specific upgrades in for the Intoxilyzer 9000 which may actually render it a better functioning machine. Some of these added functionalities include the production or the capacity to save at least a version of the histogram produced with every breath test result given by an Intoxilyzer 9000 machine. As stated previously, such information is needed and would aid in determining the functionality of the machine ensuring the results given by each machine do not show a pattern of not working or with some other possible deficiency.


Attorney Carl David Ceder and his office and team of professionals take an immense amount of pride in their work. Should you decide you would like to inquire about anything further, you can e-mail Carl directly at [email protected] and/or at [email protected], and/or call the office 24 hours a day at 460.2000.DWI(394) and/or 214.702.CARL(2275). Thank you for your time, and please contact the office with any questions and/or concerns you may have going forward or about the overall process. Phones should be answered 24 hours a day/7 days a week.