Most New Jersey motorists arrested on drunk driving charges are taken into custody after failing a breath test during a routine traffic stop. The portable breath-testing devices used by police officers in the field are not considered reliable enough to provide evidence that can be used in court, so DUI suspects are retested on more sophisticated equipment at police facilities. These machines are extremely complex and capable of accurately measuring the amount of alcohol in a suspect’s blood, but they are far from infallible.
Illegal traffic stops
The admissibility of toxicology evidence could be a moot issue if a DUI case is dismissed because the police officer involved violated rights guaranteed by the U.S. Constitution. This could happen if the officer lacked the requisite reasonable suspicion to initiate a traffic stop or ordered a motorist to take a breath test despite having no good reason to suspect they were intoxicated. The Constitution also gives the accused the right to confront all of the witnesses against them, which means a DUI case could be dismissed if the arresting officer does not appear in court.
Improper calibration
Breath test results are usually the most compelling evidence in drunk driving cases, but there are several ways they can be challenged. BAC results may be excluded and DUI charges could be dropped or dismissed if the equipment used was not properly calibrated, which is why criminal defense attorneys often seek to obtain police maintenance records when their clients are accused of operating a motor vehicle while under the influence. When breath-testing equipment is not calibrated correctly, the BAC readings generated can be as much as 40% too high.
Challenging BAC evidence on medical grounds
DUI suspects who suffer from certain medical conditions may be able to challenge breath test results even if the police acted correctly and the equipment used to measure their alleged impairment was working properly. Digestive disorders like gastroesophageal reflux disease that cause acid to accumulate in the stomach and esophagus can skew BAC results, and individuals who follow diets low in carbohydrates or suffer from diabetes may also fail breath tests because their bodies have entered into a metabolic state known as ketosis.