Understanding Breathalyzer Tests

Getting pulled over can be a very intimidating situation for anyone. This is especially true if you are stopped on suspicion of DUI, even if you have not consumed any alcohol or drugs at all. In order to be arrested for a DUI, an officer must have probable cause that you are above the legal limit for blood alcohol concentration (BAC) which is .08 percent in all states. Officers conducting roadside stops commonly use breathalyzer devices to determine if alcohol has been consumed by the driver. For this reason, the results of a breathalyzer test are often the primary reason for an arrest on suspicion of DUI.

It  makes sense why police officers enjoy using breathalyzer devices on roadside stops. These machines are small and portable, and someone can learn how to operate them without needing medical training. A breathalyzer test is considered to be minimally invasive, so it is easier for an officer to get consent to use it. It is also highly unlikely for someone to be injured if executed improperly. However, breathalyzer tests are prone to error, and false positives are returned frequently. These botched tests are unfortunately used as the basis for many DUI arrests. For this reason, it is important to seek legal assistance if you have been arrested based in part on the results of a breathalyzer test.

How Breathalyzer Tests Work

When you are being subjected to a breath test, it is very important to blow a large sample of air from deep within your lungs into the device. This allows for an accurate reading. Shallow breaths just measure alcohol present in your mouth and do not reflect accurately the body’s BAC. To achieve this, the officer must make sure that you exhale for a sufficient duration into the device for a sufficient amount of time. If the sample is too small, your test will be tainted by whatever is in your mouth, and therefore will not indicative of what is in your blood.

Breathalyzer devices begin to read your breath after it is injected into the device and makes contact with a reactive substance such as a silicon-oxide material. Any alcohol in your breath sample will create an electric current while reacting with the material in the device, and then the strength of this reaction is measured in order to determine the amount of alcohol present in your system. Unfortunately, substances from alcoholic beverages are not the only particles that create a reaction in a breathalyzer. A false positive can result from some of the following contaminating your test:

  • Microscopic fruit or sugar particles that have fermented in your mouth
  • Cigarette smoke
  • Chemicals in the air, such as hairspray or perfume
  • Mouthwash or breath mints

Breathalyzer Tests Can Be Improperly Administered

While breathalyzers are considered to be relatively easy to operate, there are still a number of things that a person must do in order to make sure that a breath sample is collected and analyzed properly. All breathalyzers function according to the same principles, and it is important that an officer follows proper procedure whether using a hand-held breathalyzer in the field, or using a larger machine at the police station. Chemical and technology experts have determined certain steps that should be followed in order to increase the likelihood of successful breath tests:

  • The officer should allow for a pre-test observation period of at least 15 minutes. In order to make sure that a person’s breath is untainted so as to allow for a proper BAC determination in a breath test, it is essential that the person does not contaminate their breath by eating, drinking, burping, or vomiting right before a sample is given. In California, the law states that officers must provide for 15 minutes of uninterrupted observation before taking a breath sample.
  • The officer should conduct a “blank” test immediately before the real test in order to make sure that the device is not incorrectly returning a positive when alcohol should not be present.
  • At least two breath tests should be conducted, at intervals of 2 to 10 minutes apart.
  • A proper control test should also be done along with a test of the suspect so as to make sure that the breath test is not being affected by any unforeseen variables.

Breathalyzer Tests Should Not Always Be The Determining Factor In A DUI

Police officers can arrest you for a DUI if they have a reasonable suspicion of your intoxication, and a breathalyzer can quickly and easily give an officer your BAC, which may lead to an arrest. There are many ways in which a breath test result can be called into question. If you were breath tested improperly, the results were likely inaccurate, and they should not be used against you. A good DUI defense lawyer can help protect your rights by challenging inappropriate evidence from your prosecution, and this can result in a favorable plea offer from the prosecutor, or in some cases – your charges being dropped altogether

Author Bio:

McKneely Law Firm is a criminal defense law firm in Fresno, CA.

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