Preliminary Breath Test
What is the Preliminary Breath Test (PBT)? It is a handheld device that is commonly called an ALCO-SENSOR, and is used by officers during a DUI investigation. There are many different makes and models of ALCO-SENSOR’s. In Georgia, the Georgia Bureau of Investigations has a list of devices in which are approved for officers to use during a DUI investigation. The device that officers use must be on this list.
How does the ALCO-SENSOR work? The officer has a person blow air into the ALCO-SENSOR. After enough air has been blown into the device, it will then display a numerical reading for the officer to see (example .078). This number is not admissible in court and the officer can only testify to the result being positive or negative. This means that any result from (.001) or above is considered positive.
Just because the number is above the legal limit does not necessarily mean that the person’s blood alcohol concentration is above the legal limit. This is because, ALCO-SENSOR’s can produce inaccurately high results due to residual mouth alcohol. Residual mouth alcohol is alcohol that is left in the mouth after a person has consumed alcohol, used mouthwash with alcohol, or a breath spray containing alcohol. Residual mouth alcohol can also be caused by a person regurgitating or burping up stomach contents that contain alcohol. The breath tests that officers use for evidential purposes have (3) safe guards in place to reduce the likelihood of residual mouth alcohol.
1. Deprivation period
This is an at least (15) minute time period that the officer must ensure that the person has not taken anything containing alcohol, or regurgitated or burped.
2. A slope detector on the Breath Testing Device
As a person blows into the machine, the alcohol concentration reading will steadily rise as the person blows more and more air into it. If residual mouth alcohol is present, the reading will rapidly rise, but then will begin to decrease as more air is blown into the machine. If the machine detects this, it will stop the test and notify the officer that there was residual mouth alcohol detected.
3. Replicate Samples
An evidential breath test requires the person to provide (2) samples separated by several minutes. These samples must be within 0.02 grams of each other. If they are not, the officer is notified of the possibility of residual mouth alcohol and the test is not valid.
This is important because an ALCO-SENSOR has none of these requirements and is susceptible to residual mouth alcohol. The manufactures of ALCO-SENSOR’s recommend that officers utilize a (15) minute deprivation period, but there is no requirement.
What is the purpose of the Preliminary Breath Test? It is to associate the impairment that an officer is observing with alcohol. This means that officers should use the ALCO-SENSOR at the end of their DUI investigation. The officer should have made their decision that they believe the person is DUI. The officer then uses the ALCO-SENSOR to determine if alcohol is causing the impairment. If the reading does not match what they are observing, then they know to further investigate the possibility of drugs. The officer will then also know what chemical test to request of the person after the arrest.
That is the way that the Preliminary Breath Test should be utilized, but that does not always happen. There are many officers and agencies that utilize the ALCO-SENSOR prior to administering the Field Sobriety Tests. There are many problems with this. The number one issue is that this can lead to bias. For example the reading is (0.120). The officer immediately has information that leads them to believe that the person is over the legal limit. Instead of using their knowledge to form an opinion that the person is DUI, they are already under the assumption that the person is. If the initial reading was elevated due to residual mouth alcohol, this could cause an officer to make an incorrect arrest decision. The likelihood of this is reduced if the officer at least uses the ALCO-SENSOR before and after the Field Sobriety Tests.
The next article is going to cover the INTOXLIYZER 9000 and the basics of breath testing.
About the author: Joshua Ott operates Caselock Inc., specializing in expert testimony and reviews for cases involving alcohol and/or drug impairment. Joshua has extensive knowledge and training obtained from ten years as a police officer in Metro Atlanta. He has extensive experience training law training law enforcement officers as well as courtroom preparation and testimony. He resides in Woodstock, Georgia with his wife, daughter and Miniature Schnauzer, Gus. For more information, visit caselockinc.com.