Are DUI Breath Tests Reliable in South Carolina?

As DUI defense lawyers in Mt. Pleasant, South Carolina, we frequently deal with the DMT DataMaster breath test machine. Not only is the DataMaster DMT a complicated piece of machinery that doesn’t always function properly, but there are also many reasons why the breath test results can be wrong.

List of Reasons Why a DUI Breath Test in South Carolina Can Be Wrong

  • Abnormal Hematocrit – Hematocrit is the ratio of red blood cells to the total volume of blood. The DataMaster DMT “assumes” a hematocrit of 47%. However, in the real world, hematocrit values range from 42% to 52% in men and from 37% to 47% in women. So, a person with a lower hematocrit will register a falsely high BAC reading.
  • Barometric Pressure – Barometric pressure impacts partition ratio because it is part of the equation behind Henry’s Law. So, as the pressure changes, so does the partition ratio of 2100:1, and so does your breath test result. In other words, anything that changes barometric pressure, including altitude and the weather, can impact your breath test results making them unreliable.
  • Breath Temperature – Remember that Henry’s Law and the partition ratio of 2100:1 depend, in part, on temperature. So, if you had a fever when you blew, your test result will be high.
  • Breathing Pattern – The DataMaster DMT is supposed to analyze any alcohol contained in deep-lung or “alveolar” air. The DataMaster DMT is supposedly designed to warn the officer if you haven’t provided enough of an air sample when you blow. This creates problems, and oftentimes false readings, depending on how the suspect blows into the machine. Essentially, the alcohol concentration in your breath depends upon whether the DataMaster DMT is testing the first or last part of your breath. When you exhale, the first part of your breath has a lower alcohol concentration than the last part of your breath. In fact, the last part of your breath can register over 50% higher than your actual BAC. Many police officers know this and sometimes tell the suspect to keep blowing longer or to blow harder so the machine will give a higher reading.
  • Endogenous Ethanol Production – The human body produces its own supply of alcohol naturally on a continuous basis, 24 hours a day, 7 days a week. It’s called endogenous ethanol production. In some cases, people naturally produce enough to register as being “legally” intoxicated.
  • Gastroesophageal Reflux Disease (GERD) – The DataMaster DMT is designed to test deep-lung air rather than “mouth alcohol.” Mouth alcohol exists at a higher concentration than alcohol in the deep lung tissue. GERD, better known as heartburn or acid reflux, causes undigested or semi-digested stomach acids (containing alcohol) to travel from your stomach back up to your mouth and throat. When stomach acid enters the mouth or throat, the DataMaster DMT will measure mouth alcohol instead of deep-lung air. As a result, the test results will register a false high reading.
  • Hypoglycemia – Hypoglycemia is low blood sugar which is a condition that occurs in diabetics. Unfortunately, about 1 out of every 7 drivers is diabetic. Some of these drivers don’t even know they are diabetic. People who experience hypoglycemia oftentimes have slurred speech, they are disorientated, they are unsteady on their feet, they are drowsy, they exhibit poor motor control, and they have a flushed face. All of these conditions are similar, if not identical, to the conditions the police look for in drunk drivers. Hypoglycemia also causes acetone in the breath which the DataMaster DMT falsely registers as consumed alcohol.
  • Improper Machine Maintenance – Over the years, our Charleston DUI lawyers have cross-examined the law enforcement officials who are responsible for keeping the DataMaster properly maintained. In many cases, we’ve found a lack of repair records that are required under SC law and maintenance procedures that weren’t followed. These problems lead to faulty BAC readings and, in some cases, “not guilty” verdicts at trial or a dismissal of the case.
  • Operator Error – In South Carolina, the law requires that law enforcement videotape the testing procedure. Many common problems that we see include (1) failure to observe the subject for at least 20 minutes before administering the test as required by South Carolina law; (2) failure to check the suspect’s mouth before the test which is also required by law; and (3) failure to properly advise the suspect of their right to refuse the test which is likewise required by law.
  • Problems with Simulator Solutions – In the DataMaster DMT, simulator solutions of water and alcohol are used during the test. If the simulators that are used to calibrate the DataMaster aren’t properly prepared or used, the DataMaster’s results are meaningless.
  • Radio-Frequency Interference – Because the DataMaster DMT is a complicated electronic device, radio frequencies (RF) can interfere with the test’s results and cause a high reading. Supposedly, the DataMaster DMT will warn the officer performing the test if the DataMaster DMT detects any RF interference. However, I’ve watched test videos that show the officer has his or her radio on or was using a cell phone, yet the machine doesn’t report any RF interference. Warning or no warning, RF will impact the test’s reading.

If you think we’ve covered just about everything relating to DUI defense, we can assure you that there is much, much more. But by now you should be getting the big picture – DUI’s are complicated, and “complicated” means MANY ways to defend you from a DUI!

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