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Breathalyzer Calibration

Driving under the influence of alcohol or drugs (DUI) is a serious criminal offense. To protect communities and to reduce drugged and drunk driving accidents, states have strengthened DUI laws. A DUI arrest can result in a driver's license suspension, even before a conviction. Possible penalties include mandatory jail time, large fines, substance abuse treatment, and an ignition interlock device requirement.

DUI Charge Basics

Every state's DUI laws have per se DUI offenses. A per se DUI is the legal presumption of intoxication if your blood alcohol concentration (BAC) is at or above a specific limit. Most states have a per se legal limit for drivers 21 or older of 0.08%, except for Utah, which has a limit of 0.05%. If your BAC is at or above your state's legal limit, law enforcement can arrest you on a DUI charge. They don't need any other proof of your intoxication.

In most states, you can still face a DUI arrest when your BAC is below the per se legal limit if you appear and act intoxicated and are unsafe to drive. Law enforcement will need more evidence of your intoxication to maintain this type of charge.

But how does law enforcement determine the amount of alcohol in your system? To establish a DUI suspect's BAC, police officers will ask a driver to submit to testing. While a blood test produces more precise results, police officers regularly use breath testing devices to estimate your blood alcohol content at the time of your traffic stop.

What Is a Breathalyzer?

When a law enforcement officer stops you under suspicion of DUI, they will ask you to take part in sobriety testing. This may include field sobriety tests, a preliminary breath test, and chemical testing.

An officer conducts a preliminary breath test with a handheld breath testing device or a Breathalyzer machine. These breath testing devices require you to provide a breath sample by blowing into the machine. The instrument will register your BAC level.

While this type of measurement offers strong evidence about your BAC, it is not infallible. Courts regularly accept Breathalyzer evidence as sufficient proof of your BAC when law enforcement uses evidentiary testing machines. Law enforcement agencies must show that the testing device can produce reliable results. Your DUI case may get dismissed if the Breathalyzer device isn't calibrated.

Law enforcement doesn't usually rely on the preliminary breath test alone. This preliminary measurement gives the officer probable cause for arrest but isn't often used in court. The officer will ask you to submit to further chemical testing to establish your BAC and to look for illegal drugs. Chemical tests may include blood, urine, or oral fluid testing. You may also need to complete another breath analysis with a more sophisticated breath-testing machine.

Implied Consent

All states have implied consent laws. Under implied consent laws, you have already consented to chemical testing by possessing a driver's license and driving on roads and highways. When a police officer suspects that you are driving under the influence of intoxicants, they will ask you to submit to chemical testing, such as a breath test or blood and urine test.

You may refuse chemical testing, but under implied consent laws, you will face penalties. The penalties vary by state. Penalties may include driver's license suspension, fines, and possible criminal charges.

Common Challenges to Breathalyzer Results

The most frequent challenges to Breathalyzer evidence concern whether a breath test device was in proper working order at the time of the test. Breathalyzers and breath testing devices need regular calibration and maintenance to deliver results accurately. An improperly calibrated or poorly maintained machine will produce unreliable results. These cannot form the basis of a presumption of intoxication under per se DUI laws.

Certain medical conditions and medications may influence your BAC test. Recent mouthwash or breath freshener use can affect results if they contain alcohol. Diabetic ketosis, hypoglycemia, and serious heartburn or acid reflux may alter test accuracy as well. Recent smoking or vomiting can contaminate your breath sample. Officers know these may impact the results and usually take precautions to prevent them.

Use of a nonapproved device can get your test results thrown out of court. A defense lawyer can research which machines your state approves for use.

How Often Should a Breathalyzer Undergo Calibration?

It depends. Each state has laws and standards about when and how breath-testing devices must undergo calibration. Often, a device must be calibrated after several uses or at regular intervals, like every 30 days. For the results of a test to be admissible in court, however, most states follow these basic guidelines:

  • The breath test must capture at least two measurable readings that are within 0.02% BAC of each other.
  • The breath device must be on a conforming list of approved acceptable devices.
  • The breath device must be properly maintained and checked for accuracy at regular, set intervals.
  • The person administering the test is certified in the use of that particular device.
  • The person administering the test must do so following their training.
  • The person administering the test must ensure the test subject does not burp, regurgitate, eat, vomit, or smoke for a period immediately before the testing sequence.

How Do You Show That a Breathalyzer Wasn't Working?

Suppose a defendant can show that the police department did not follow proper calibration procedures or that the device provides erroneous readings. In that case, a court will likely declare the results of a Breathalyzer test inadmissible as evidence of your intoxication.

A criminal defense attorney can subpoena the maintenance and calibration records of the breath testing device you tested. These records prove the equipment was not properly tuned to deliver reliable test results.

At that point, the burden will shift back to the prosecutor to prove your intoxication through other evidence. Evidence can include testimony about the odor of alcohol on your breath, red or watery eyes, bad driving, poor performance on roadside field sobriety tests, or a car accident.

A DUI Attorney Can Challenge the Breathalyzer Calibration in Your Case

Facing a DUI charge can be overwhelming. A DUI attorney can help you navigate the system and provide valuable legal advice. They will be able to discuss the validity of your Breathalyzer results and challenge the breath test calibration. An excellent first step to defending your rights and getting the best possible outcome for your case is to contact a local DUI attorney.

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