In the majority of drunk driving criminal cases, the most compelling pieces of evidence are test results showing the defendant's blood-alcohol concentration at the time of arrest. Blood tests tend to produce the most accurate results, but they are obviously impractical to conduct out on the road.
Therefore, police departments in West Virginia and across the country rely on breath testing devices, commonly referred to as breathalyzers. In some cases, a breathalyzer test is followed up with a blood test after the suspect is arrested. Regardless of which testing method was used, test results showing that the defendant had a BAC at or above 0.08 percent may be sufficient to secure a conviction - unless a defendant can provide evidence that the testing device did not take an accurate reading.
There are two common strategies defense attorneys use when challenging breathalyzer test results. The first is to show that the device itself was faulty (or potentially faulty) due to improper maintenance or calibration. Breathalyzer devices must be serviced regularly and calibrated to ensure that they are taking accurate and consistent readings. Your defense attorney may be able to subpoena a specific device's maintenance and calibration records to determine if errors could have been made.
The second common strategy is to argue that the reading was inaccurate because the test was administered incorrectly. Breathalyzers are only as accurate as the manner in which tests are conducted, which is why police officers must go through training on how to use the devices and administer the tests.
For instance, a test administered soon after a suspect took his last drink would likely produce a reading that was too high. This is because alcohol still in the mouth could be detected by a breathalyzer. Therefore, police are supposed to wait a certain period of time before administering a breathalyzer to ensure that test results won't be skewed. Other behaviors that could skew test results (if done too close to testing) include burping, vomiting, eating and smoking.
If you are facing DUI charges, the evidence against you may seem strong. But such evidence can be challenged, and an experienced criminal defense attorney will know how to find weaknesses in the test results and in the case against you.