FREE Case Evaluation

MD DUI Breath Testing Instruments and Procedures

After a driver is pulled over and upon completion of a series of standardized field sobriety tests (SFSTs), the police officer may believe there is cause to administer a preliminary breath test (PBT) at the scene. A Maryland DUI lawyer will inform you that you are not required to take a standardized field sobriety test (SFST); however, this may make the officer want to administer the PBT.

This test requires the person to blow into a machine that measures the amount of alcohol on the person’s breath and then shows a number on a small screen that is an interpretation of how much alcohol is in a person’s body.

The RBT “breathalyzer” is a portable device, which estimates the suspect’s blood alcohol concentration (BAC). Coupled with, or in lieu of, the SFSTs the officer will rely upon the PBT results to determine whether to arrest the driver for DUI.

Maryland law enforcement agencies use one of two breathalyzer machines in a DUI investigation: the Intoxilyzer and the newer Intoximeter. The Intoxilyzer has been the standard breath-test machine employed by law enforcement since the 1970s. And even newer models have been in use for over 15 years. Intoxolyzers use a different and more accurate process than Intoximeters’ to determine BAC.

To capture reliable breathalyzer evidence, the suspect must blow into the machine twice within a few seconds of the other. This creates two separate breath sample readings. If the difference between these two readings is larger than 0.02, the machine will request that the suspect immediately provide a third breath sample.

Breath Tests as Evidence in Court

Before a scientific test can be admitted as reliable evidence in court, the relevant scientific community must stringently test and retest the device and develop procedures that verify its dependability.

Law enforcement has conducted the only reliability test for the Intoxilyzer, which means that further testing must take place for Intoxilyzer readings to be declared scientifically reliable. Furthermore, Intoxolyzers have a reputation for constantly needing re-calibration.

External Factors Which Can Affect Breath Test Accuracy

There are many “mitigating” issues that may also affect the accuracy of a breath test, such as:

  1. Cell phone or radio interference with both fixed and remote breathalyzers, especially newer models
  2. Power surges in fixed, as in non-remote, devices that are found in police stations
  3. Machine malfunctions
  4. Variances in the subject’s body and breath temperature, or that of the machine at the time the test is administered
  5. Improper officer training
  6. Improper machine maintenance
  7. Subject’s exposure to certain chemicals, primarily those that affect the body’s pH factor
  8. Mouth contaminants, such as smokeless tobacco, dentures, mints, or lip balm

Physical Conditions That Can Alter Breath Test Readings

In addition to the multitude of mitigating issues that can call into question a breath test’s accuracy, there a a number of common physical conditions people suffer from that can also adversely effect breath test machines, including:

  • Esophageal hernia
  • Diabetes
  • Liver disease
  • Chronic heartburn
  • Lungs diseases such as cancer, emphysema, or COPD
  • Certain diets

Accuracy of Breath Test Readings

Men and women’s bodies are different even though breath test machines treat them the same. This is another basis for PBT tests to be suppressed in court. For example, alcohol affects women differently than men because women do not metabolize alcohol as quickly as men do. Women have a lower ADH enzyme level. This causes a larger proportion of ingested alcohol to reach the bloodstream more quickly and remain in their system longer.

Thus, a woman will often show a higher BAC reading than a man who might be the same size as the woman and drinks the same, or a modestly larger, amount of alcohol.

Research has also proven that breath-testing machines are frequently calibrated according to an average male’s anatomy. This is inherently unfair, because women have different body compositions, lung capacities, alcohol-absorption rates, and body-water content levels as compared to men. This can lead to inaccurately higher breath scores for women as compared to men. It should also be noted that the above calibration methods might also improperly reflect the level of intoxication in significantly smaller-than-average men.

Breath tests are often challenged because there is a litany of controversy regarding the validity of these tests due to faulty machines, calibrations, variances in body types, gender, and mitigating health conditions that can affect the results.

For many years, Maryland has experienced questionable data generated from PBT machines, including the Intoxilyzer 5000 EN. Therefore, the state has started using machines that are believed to be more accurate. Nevertheless, an experienced Maryland DUI defense attorney is aware of developments made regarding breathalyzers to ensure their clients are not unfairly convicted due to incorrect or improper administration of any BAC tests.