The DUI Chemical Test Known as the Breath Test

 

In order to charge someone with driving under the influence (DUI) the arresting officer must have evidence that the person is indeed impaired. This evidence typically comes from one of three tests: a blood test, a breath test or a urine test. These tests measure the amount of alcohol found in a person's body, called the BAC. Of the 3 tests the breath test is probably the most commonly used. However, this test is not even close to 100% reliable and can be prone to serious error.

 

Nature of the Breathalyzer / Breath Test

 

The suspect exhales into a device that has chemicals used to detect the presence of alcohol-like compounds in a person’s breath. This measurement is then used to project the amount of alcohol within the person's body. The breath test may be conducted using a portable model of the machine (PBT – preliminary breath test) or it may be conducted using a large and more expansive machine located at the police station known as a breathalyzer.

 

Option to Take the Test

 

Most people erroneously think that taking the test is mandatory. Whether the test is compulsory or voluntary depends on your state’s laws, so check first before you refuse a breath test. One option when an officer requests you to take a breath test is to ask the police officer if you may first speak to an attorney. If you are given the opportunity to speak to an DUI attorney you should follow his or her advice regarding the tests and what to say to the officers.

 

Differences in the Types of Tests

 

The test conducted in the field with the portable device is called a Preliminary Breath Test (PBT). Most of these devices have a screen that reads out the test results. However, these results cannot be printed. For this reason, the preliminary test results are not usually allowed as evidence in court. This is the primary reason that suspects have for being able to decline this particular test. Furthermore, a sample of your breath is not saved inside the machine and any evidence that shows your BAC is effectively lost.

 

If a person agrees to the preliminary test and it shows a BAC (blood alcohol concentration) above the legal limit this is enough cause for the officer to take the person into custody and have them tested further at the police headquarters. Even if the person successfully completes all of the other sobriety tests, the breath test will likely be used as probable cause to arrest the person and charge them with drunk or drugged driving.

 

The other test is called the Evidentiary Breath Test. This machine does have the ability to print the test results. Therefore this evidence can be used in a court of law.

 

All states have in place certain rules and guidelines regarding the use of the evidentiary testing apparatus. The rules govern how the test is administered, the required maintenance of the machine, and which quality checkpoints are in place. A DUI lawyer will examine every step of this process to see if any mistakes were made. With so many details and rules to abide by it is quite possible that an item will be overlooked or human error will creep in.

 

Problems with the Actual Test

 

The breath tests follow a simple formula to deduce the amount of alcohol in a person's bloodstream. The presence of alcohol in the breath is calculated. This number is then multiplied by an average. The resulting number is supposed to accurately represent the person's BAC. However, everybody is not average.

 

People all over the world have different physical characteristics. Some people have slightly high blood pressure while another person has slightly low blood pressure. One individual may have a typical body temperature of 99.2 while another individual will have a temperature of 97.3. These variances in people's bodies make the accuracy of a breath test questionable at best.

 

Defending Against Breath Test

 

Most experienced DUI attorneys feel that there are ample opportunities to not only defend against an alcohol breath test. The possibility for human error during the testing procedure is usually a good starting point. If a evidentiary test was conducted and it shows a BAC above the legal limit the next point to argue would be the person's unique chemical composition. If medical records and testimony from a doctor can prove that the person is above average when it comes to absorbing alcohol then it can be argued that the breath test showed a higher BAC due to the person's chemical makeup.