Determining whether a driver is impaired by alcohol seems relatively easy. Often, police can smell alcohol on a driver’s breath, but a test of a driver’s blood alcohol concentration is usually the per se indicator of impairment. A driver with a BAC of .08 percent or higher is over the legal limit in Louisiana and most other states.

While it sounds fairly straightforward, it is not always foolproof. Devices used to measure your BAC are not always reliable, and roadside tests can be too subjective to hold up in court. Therefore, it makes sense that the tests and procedures police use to detect whether you are under the influence of drugs might be similarly unreliable.

Testing for drug impairment

Law enforcement agencies across the country are dealing with the increasing problem of drugged driving. This includes not only illegal substances like marijuana but also legitimate prescription medications that can cause impairment. Since there is no single and convenient test, such as a breath test, to detect drugs in your system, officers who suspect you of driving while drugged may call in trained drug recognition experts who will test you using multiple steps, including:

  • Examining your pupil reaction and the movement of your eyes
  • Questioning you about your lifestyle and drug habits
  • Looking for track marks on your body
  • Subjecting you to balance and coordination tests similar to roadside sobriety tests
  • Testing your blood, urine and saliva

As you can imagine, this process takes about 45 minutes, much longer than a BAC test, and in many ways, it is just as subjective. While police departments rate their success for accurately assessing a driver on drugs at about 80 percent, some independent studies claim DREs are correct about half the time.

Who is right?

While courts typically accept the lab results in an alcohol-related arrest, DREs receive training to reject any test results that contradict their own observations. In other words, if a DRE interviews you, observes your actions and vital signs, and concludes you were driving under the influence of drugs, that DRE is likely to stand by his or her conclusion even if subsequent blood analyses show no evidence of drugs in your system.

If you are facing charges of driving under the influence of drugs, you have a lot at stake. Drugged driving is becoming a common cause of traffic injuries and fatalities, and law enforcement is vigilant in its efforts to get such drivers off the road. To ensure your rights are protected every step of the way, you may benefit from the representation of a skilled defense attorney.