Breath Testing in DUI Cases

Law enforcement officers in Michigan are authorized to administer a chemical test of a person's breath, blood or urine if he or she is lawfully arrested on suspicion of operating while intoxicated (OWI). The type of test administered is left up to the officer. Urine tests are very rarely used in these situations, and breath tests are still more common than blood tests for determining blood alcohol content (BAC) in OWI suspects.

Of these three methods, the breath alcohol test is by far the most common. And while it is sure to be a key piece of the prosecution's evidence against you, this test is also a central point of attack for the defense team.

The machine used to conduct breath BAC tests in Michigan is called the DataMaster DMT. This is the only breath testing machine recognized as evidentiary by the state. In other words, only results of breath BAC tests taken on a DataMaster will be admissible as evidence in court. Tests taken on any other machine will not be recognized by the state.

Also, only certified operators may administer tests on this machine, and if the officer who administered your test was not certified, the results of the test may be inadmissible in court.

The DataMaster works by a process called infrared spectroscopy. Put very simply, the machine determines a BAC result by a calculation based on the presence of alcohol molecules and the amount of light that is absorbed at one end of the testing chamber. In order to make this calculation, the machine must take into account several other factors, many of which are pre-programmed based on assumed averages.

For example, the machine operates on the assumption that the test subject's body temperature is within a "normal" range. This means that if you have a higher than normal body temperature at the time of testing, the test result will be higher as well.

One of the problems with infrared spectrophotometry, or the DataMaster in general, is the fact that the infrared light doesn't know how to distinguish between ethanol, which is beverage alcohol, or other types of molecular chemicals that have the same basic structure.

For example, things like acetone also have a molecular signature, or fingerprint, that looks to the machine very much like an alcohol molecule. So, if you have acetone in your breath, as many diabetics do, as do people on the atkins diet, then the machine will falsely interpret the acetone in your breath as alcohol. This will lead into a false high result.

Law enforcement agencies must designate DataMaster operators who are required to attend training on how to properly maintain the machine and administer the test. If a non-certified officer administers the breath test, the result will be thrown out of court.

The certified officer must also keep detailed maintenance and accuracy logs for the machine. If the DataMaster is not properly maintained and regularly tested for accuracy, the results may not be admissible.

Officers must follow very specific procedures when administering the breath test. If these steps are not followed precisely, the results can be skewed. For example, the officer is required to observe the suspect for 15 minutes prior to administering the test in order to ensure there is no regurgitation into the mouth and that no foreign objects or substances are put into the mouth. The machine is designed to test alcohol from the deepest part of the lungs, and alcohol that is present in the mouth can inaccurately elevate the reading.

If the officer failed to observe you for 15 minutes prior to administering the breath alcohol test—or if you placed anything in your mouth or regurgitated within 15 minutes of taking the test—then the results may have been skewed. Based on this, a skilled defense attorney may attack the BAC test and possibly have the results thrown out as evidence.

There are several medical conditions that can cause inaccurate DataMaster readings. These include:

• Diabetes
• Hypoglycemia
• Gastro esophageal reflux disorder (GERD)

Additionally, blood in the mouth can potentially cause a flawed reading, as can dentures, mouth guards and other dental devices that may trap alcohol in the mouth.

The official breath test, or a blood test for that matter, either can be defended based on three different categories of defenses. One category of defense is based on a violation of the law. In other words the police officer violated some technical aspect of the law which makes the breath, blood or urine test inadmissible. The second category of defense relates to the manner in which the test was processed.

Whether it be breath, blood or even urine, there is the opportunity for human error in the way that the sample is handled or the way that it is tested. Either of those two things can lead to an inaccurate or unreliable result. The third category of defense would relate to the individual. Specifically there is something about the individual's anatomy or physiology that could make them an inappropriate candidate for either breath, blood or urine testing. In those particular instances the physiology or the anatomy of the person makes the test unreliable.

You may have heard that putting copper pennies in your mouth before taking a breath alcohol test will fool the machine. Some people say that the pennies will cause the machine to produce an outrageously high blood alcohol content (BAC) reading—so high, they say, that no judge would ever believe the reading to be accurate. Others have said that a copper penny will mask any traces of alcohol in your mouth, thereby tricking the machine into producing a negative reading.

The truth is, putting pennies (or any other form of currency) into your mouth will have zero effect on a BAC breath test result. Evidentiary breath testing machines are designed to test the air from the deepest part of your lungs, also called alveolar breath. It is true that residual mouth alcohol can impact a BAC breath test result; however, the penny trick has been shown to have no noticeable effect on a breath test.

Another problem with this myth is that in Michigan, law enforcement officers are required to observe you for 15 minutes prior to administering a breath alcohol test. This is done specifically to ensure that you do not regurgitate or place anything into your mouth before blowing into the machine. Therefore, putting pennies in your mouth prior to taking the test without an officer noticing is highly unrealistic.