If you have been pulled over for a DUI, you have probably been offered a breathalyzer test. You may not have known that you have the right to refuse the test, and taken the breathalyzer without fully understanding how it works. After this happens, you are often left wondering if your breathalyzer results are accurate, and how you can attack them at trial if they aren’t. Below we will discuss everything you need to know about breathalyzers.

Breathalyzer vs. Blood Draw

When an officer pulls you over, they will begin by asking you to participate in standardized field sobriety tests (SFSTs). You have the right to refuse these. After you either participate in or decline the SFSTs, the officer will ask you to take the State’s test, which is either a breathalyzer test or blood test.

There is no doubt that a blood draw is more accurate than a breathalyzer, but you do not get to choose which one you are given. As with the SFSTs, you can refuse to take either test.

Accuracy and Issues With a Breathalyzer Test

Modern breathalyzer test results are fairly accurate. The main issue with these tests is procedural—namely, the deprivation period. Breathalyzer tests are designed to measure the alcohol concentration within your lungs. However, any alcohol remnants within your mouth can create a false reading and make your blood alcohol content (BAC) read significantly higher than it actually is. To ensure the validity of breathalyzer results, officers must administer what is called a deprivation period. This is a 15- to 20-minute time period where the officer observes you, allowing any alcohol in your mouth to dissipate so the breathalyzer reading is accurate.

If the deprivation period is not followed, your breathalyzer results could be inadmissible at trial. This allows your attorney to argue that the breathalyzer reading was falsely conflated due to presence of alcohol on your breath, rather than in the lungs itself.

Another issue with the breathalyzer test is the margin of error, which. can be .01 higher or lower than the reading. If your BAC is on the verge of the legal limit, this tiny margin of error could be the difference between receiving criminal charges and not being charged at all. For example, if your BAC is a .07 and the legal limit is a .08, that margin of error could cause your breathalyzer results to read as a .08 and lead to a DUI arrest.

While this margin of error can be argued in an attempt to prevent the breathalyzer results from being admitted at trial, a judge will most likely reject that argument. If your argument is rejected and you feel the margin of error is to blame for your breathalyzer reading, the only course of action is to hire an expert to testify at trial and hope to convince the jury to disregard the breathalyzer results.

In most cases, the margin of error doesn’t make a significant difference in the breathalyzer reading and therefore doesn’t affect the outcome of the case. However, if you are directly at a .08, the margin of error could mean the difference between a conviction and a lack of charges.

Accuracy and Issues With a Blood Test?

Most blood draws are admissible because they are extremely accurate, and it is rare that your attorney can find a way to keep the results out of trial. Not only do blood tests have a high degree of accuracy, but they show a wider range of intoxicants than a breathalyzer.

A breathalyzer will only show your BAC. A blood draw will show ANYTHING that is in your system, including marijuana or prescription medications. This can lead to charges for a DUI under a combined influence of alcohol and drugs, which requires a lower BAC.

The most common issue with blood draws lies not in the test itself, but again, in a procedural element. In order to draw blood for the State’s test, the officer must get your consent first. If you do not give consent, the blood test results are inadmissible.

The only other issue lies in the way the blood is stored. If the blood is stored improperly before testing, it can ferment and the alcohol level can read higher than it actually is. However, this is very uncommon as the blood is handled by experienced medical professionals.

What Happens if You Think Your Test was Inaccurate?

If you believe your breathalyzer or blood test results were inaccurate, you need to tell your attorney right away. You do not want to make this argument for the first time at trial; your attorney will submit a motion to the judge ahead of time.

A motion is a written argument regarding one piece of evidence, and it involves a question for a judge rather than a jury. A jury answers factual questions, like whether a defendant was drunk. A judge addresses legal questions, such as deciding which evidence is admissible at trial and whether the defendant’s rights were violated during the traffic stop.

After assessing either written or oral arguments from your attorney and the prosecutor, the judge will determine whether the State’s test is reliable and therefore admissible, or unreliable and therefore unusable at trial. Occasionally, the judge will make a middle-ground decision and admit the test at trial, but allow the defense to present arguments that it was inaccurate and attempt to sway the jury.

The Bottom Line

Most of the time, the results of your breathalyzer test are accurate. While they might not provide as much information as a blood test would, the breathalyzer provides a fairly accurate reading of your BAC.

This does not mean the test is foolproof, and any issues you observed both before and during the test should be brought up to your attorney. If you have been charged with a DUI and are questioning the results of your breathalyzer or blood test, contact us for a free consultation.