Any test, no matter how carefully developed or well administered, can occasionally have inaccurate or inconclusive results. Standardized testing systems simply do not work well for all people. This is true of standardized testing in schools, as well as medical and chemical testing of the human body.
The system used for chemical breath test during roadside traffic stops is a perfect example. When law enforcement officers suspect that someone may be under the influences of alcohol while driving, they have the right to request that that person perform a chemical breath test as part of a roadside stop or enforcement checkpoint. Failing such a test often results in immediate arrest, as well as criminal charges.
However, far from being universally accurate, chemical breath tests cause as many problems as they solve. They are susceptible to issues caused by user error, as well as false positives related to both improper maintenance and medical issues in the subject taking the test. Similar issues will, no doubt, plague other breath testing systems, like the reported marijuana breath test currently in testing.
Chemical breath testing doesn't just look for alcohol
One of the most pervasive myths about chemical breath tests is that these tests definitively show presence of alcohol in a person's system. While it is true that alcohol in the human body will show up in breath test, other chemical compounds can also cause a positive test result.
The test scans the analyzed air that the person exhales for a group of compounds that includes alcohol, as well as other common chemicals. Anything from mouthwash to uncontrolled diabetes could impact the accuracy of a breath test.
Law enforcement will typically arrest anyone with a positive result, even if it is possible that a medical condition contributed to the positive test result.
Officers need to have proper training
Although chemical breath tests are meant to be quick and simple to administer, they still depend on proper use by the person administering the test to ensure accurate results. Mistakes by the person giving the test could result in inaccurate readings and an unfounded arrest of an innocent driver. Officers need to know how to perform the test, as well as how to accurately read the results.
Proper calibration of the testing unit is important
In order to produce reliable and accurate responses, breath tests require both maintenance and regular calibration, as well as battery replacement and software upgrades. An uncalibrated unit could provide inaccurate results. Improper maintenance could also lead to system malfunctions or other issues that compromise the validity of a breath test.
If you find yourself facing impaired driving charges and question whether the breath test administered by law enforcement was accurate, you should discuss your situation with a criminal defense attorney. It may be possible to challenge the results of the breath test.