Breathalyzer Test FAQ

If you are pulled over on a suspicion of driving under the influence of alcohol, the officer may ask you to consent to a breathalyzer test. The results of the test will be used, along with other pieces of evidence, to determine whether you are impaired beyond the legal limit. It is important to point out that a driver could still be charged with DUI regardless of the measurement registered by the breathalyzer device.

Just How Does a Breathalyzer Test Work?

A breathalyzer test involves blowing into a small tube. The air that passes through the tube is collected by a machine that analyzes its contents. In a matter of seconds, a police officer or anyone else administering the test can gain a rough estimate of how much alcohol is in your blood.

How Accurate Are Breath Tests?

While less accurate than a blood or urine test, a breathalyzer test is generally considered accurate enough to use when criminal charges are filed. During trial, test results can also be used as evidence that a driver was intoxicated at the time of a traffic stop or at the time of an accident.

What Methods Do Officers Use to Determine Your BAC?

There are several methods that a police officer can use to determine an individual's blood alcohol content. First, the breathalyzer test is used to measure the amount of alcohol in a person's breath, and that number is converted into an estimate of how much alcohol would be in a person's blood. This is the most common type of test done during traffic stops.

Field sobriety tests may also be used to indicate whether an individual is impaired by alcohol. While there is no way to measure an accurate BAC level from such tests, they do indicate if a driver has trouble walking, is slurring his or her speech or is otherwise showing signs of impairment.

Blood and urine tests are often conducted at a police station or jail. They are among the most accurate tests available and may directly measure how much alcohol is in a person's system. However, the U.S. Supreme Court has ruled that a warrant must be issued prior to any blood test, and the law is unclear as to whether one is required for a urine test as well.

Is it Possible to Challenge Breath Test Results in Court?

There are many ways in which the results of a breathalyzer test may be challenged in court. First, it may be possible to argue that the breathalyzer machine used in a particular test was not manufactured properly or certified by the manufacturer. Another challenge that is sometimes successful is directed at how the machine was calibrated.

It may also be possible to challenge the results of the test because it was not conducted according to state law. For instance, Pennsylvania requires that two tests be taken 10 seconds apart from each other.

Another argument could be that the test was flawed because too much time had passed between the time you started driving and the time that the test was taken. In some cases, an individual's blood alcohol content can actually increase after he or she stops drinking.

Are the Smaller Consumer Models of Breathalyzers Accurate?

In general, portable units manufactured and sold for personal use are almost as accurate as those used by the police. However, most companies that make or sell such units advise that people should not solely rely on them to decide if they are impaired or not. This is because age, gender and personal tolerance level could also play a role in whether they are too drunk to drive.

Should I Get Help From a DUI Attorney?

If you are facing charges of driving under the influence, it may be advisable to seek a free consultation from an attorney. The type of defense strategy that might be used will depend upon the particular circumstances of your case, beginning with whether the law enforcement officer had reasonable suspicion to make the initial traffic stop.

The information on this page is meant to provide a general overview of the law. The laws in your state and/or city may deviate significantly from those described here. If you have specific questions related to your situation you should speak with a local attorney.

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