How Police Detect Drug-Related DWI in Texas — And Where Errors Happen

Methods Police Use to Detect Drug-Related DWI in Texas

• Field Sobriety Tests (FSTs): Field Sobriety Tests are a common method that law enforcement officers use when they suspect a driver is impaired. These tests typically include the walk-and-turn test, one-leg stand, and horizontal gaze nystagmus (HGN) test. These tests are designed to assess a driver’s coordination, balance, and ability to follow instructions. While FSTs are effective for detecting alcohol impairment, they are not specifically designed to detect drug-related impairment. In fact, various factors, such as medical conditions or fatigue, can lead to poor performance, making these tests prone to error. Challenges of FSTs: FSTs are highly subjective, and their results can be influenced by numerous factors. For example, a person who suffers from a medical condition like vertigo may have difficulty with balance, leading to a false indication of impairment. Additionally, stress and nervousness can also affect how someone performs during these tests. These factors can easily result in a wrongful arrest if the officer misinterprets the results of the FST.
• Drug Recognition Expert (DRE): A Drug Recognition Expert (DRE) is a police officer specially trained to identify the symptoms of drug impairment. DRE officers are trained to assess a person’s physical and mental state and identify whether drugs are impairing their ability to drive. This process involves a detailed evaluation that includes checking the individual’s vital signs, eye movements, and coordination. The DRE will also ask about the person’s medical history and behavior. Limitations of the DRE Evaluation: While DREs are trained to detect specific signs of impairment, they are still human and subject to biases. An officer may misinterpret certain behaviors or physiological signs, leading to an inaccurate assessment. Furthermore, DREs rely heavily on their experience and judgment, which can sometimes result in misdiagnosis. If a DRE officer fails to recognize the signs of medical conditions or fails to account for variables like anxiety, the evaluation may incorrectly indicate drug impairment.
• Chemical Testing: Blood and Urine Tests: If a driver is suspected of being under the influence of drugs, law enforcement officers may request blood or urine tests. These tests can detect a variety of substances, including prescription drugs, illegal drugs, and over-the-counter medications. Blood tests are often the most reliable, as they can measure the exact concentration of a substance in the bloodstream. However, urine tests are often used as well, though they are less accurate in determining whether the driver was impaired at the time of driving. Both types of tests can show evidence of drug use, but they may not be able to conclusively prove impairment at the time of the stop. Challenges of Chemical Testing: Blood and urine tests are useful in detecting the presence of drugs, but they do not necessarily indicate whether a person was impaired at the time of the offense. Certain drugs can remain in a person’s system for hours or even days after use, making it difficult to determine whether the driver was impaired at the time of the stop. For example, marijuana can stay in the bloodstream for up to several days, even if the person is no longer under the influence. This poses a significant challenge in cases where the drug’s effects have worn off by the time the test is administered.

Common Errors in Drug-Related DWI Investigations in Texas

• Misinterpretation of Field Sobriety Tests: Field Sobriety Tests are subjective by nature, and even experienced officers can make mistakes in their evaluation of a driver’s performance. For example, a person may fail an FST due to medical reasons, such as a disability, and yet the officer may incorrectly assume impairment due to drugs. Since FSTs are not designed to detect drug impairment specifically, there is significant room for error when they are used to assess drug-related DWI.
• False Positives in Chemical Testing: Blood and urine tests are not foolproof. Certain medications, even those that are legal and prescribed by a doctor, can trigger a false positive result. For example, over-the-counter cold medications or antidepressants may show up in a blood test as drugs that can impair driving, even if they don’t actually impair the driver’s ability to drive. This is why it’s essential to challenge chemical test results if there is any doubt about the accuracy of the test or the chain of custody of the sample. 
• Errors in Drug Recognition Expert (DRE) Assessments: While DREs are trained to detect the signs of drug impairment, they are not immune to mistakes. A DRE officer may misinterpret a driver’s behavior or fail to account for underlying medical conditions that could cause the same symptoms as drug impairment. For instance, an officer may mistake a driver’s nervousness or stress for signs of drug use, leading to an incorrect diagnosis. These misjudgments can be critical in the outcome of a drug-related DWI case.
• Inconsistent or Mishandled Evidence: Proper evidence handling is crucial to the success of any DWI investigation. However, errors in the collection or handling of evidence can lead to the dismissal of charges or reduced penalties. If law enforcement fails to follow proper procedures when collecting blood or urine samples, or if there are discrepancies in the way the samples are stored and transported, the evidence may be deemed inadmissible in court. This is one area where an experienced attorney can make a significant difference, as they can carefully review how evidence was handled and challenge any inconsistencies.

Why You Need a Skilled DWI Attorney in Texas

To learn more about this subject click here: What’s the Difference Between a First Offense DUI and a Second Offense DUI?