Drivers accused of getting behind the wheel after drinking or taking drugs often believe the evidence against them is overwhelming and mounting a defense is futile, but that is not necessarily true. Prosecutors in Indiana and around the country usually rely on breath or blood test results to establish intoxication in drunk driving cases, but this evidence may not be admissible in court if the police officers involved initiated traffic stops for no good reason or made procedural mistakes during field sobriety or toxicology tests.
Traffic stops
Police officers must have a reasonable suspicion that a crime is being committed to pull vehicles over. Stops are justified when police observe traffic laws being violated, they see vehicles with equipment issues like broken windshields or malfunctioning lights or they receive calls from concerned motorists about a possible drunk driver. Weaving across lanes, erratic movements or excessively slow driving could also give an officer reasonable suspicion to signal a vehicle to pull over. Traffic stops that violate rights protected by the Fourth Amendment are considered illegal, and any evidence discovered as a result of such a stop is inadmissible.
Breath tests
The results of roadside breath tests may provide police officers with probable cause to arrest motorists for suspicion of drunk driving, but they are not reliable enough to be used in criminal courts. This is why OWI suspects usually take a second breath test at a police facility that is conducted with more sophisticated equipment. However, this toxicology evidence can only be used in court if the breath-testing equipment was properly maintained and calibrated and the officer conducting the test was certified to use it.
Medical issues and ketogenic diets
There are situations where experienced criminal defense attorneys could seek to have OWI charges dismissed even when traffic stops were justified and breath tests were conducted properly. Attorneys could challenge drunk driving charges when their clients suffer from medical conditions like diabetes that can raise acetone levels significantly or gastroesophageal reflux disease that can push alcohol into the mouth and skew breath-test results. Diets low in carbohydrates can also produce misleading blood alcohol concentration readings.
