Police officers who suspect people of illegal activity generally start looking for evidence immediately. Suspicions of drunk driving often lead to traffic stops and then potentially to someone’s arrest. A police officer who believes they have witnessed a driving under the influence (DUI) offense may gather several different types of evidence to support the allegations that they make against a motorist.
Anyone hoping to fight DUI charges needs to understand how the state proves a violation occurred. They can then prepare to challenge or explain that evidence at trial. For example, the following types of evidence typically play a role in DUI cases.
A driver’s conduct in traffic
Frequently, DUI investigations begin even before a traffic stop occurs. Officers notice someone sporadically braking without reason or swerving across the road. They likely capture footage of that on their dashboard camera. That conduct or statements from people involved in a crash with a potentially impaired driver can be key proof that they didn’t operate a vehicle like people typically do.
Field sobriety tests
When someone’s behavior at the wheel or their answers to questions during a traffic stop raise more questions instead of resolving them, officers may ask someone to exit their vehicle. Having drivers conduct field sobriety tests allows an officer to gather evidence that supports their claim of chemical impairment. Video footage and testimony about someone’s performance on those tests can play an important role in criminal proceedings.
Chemical test results
Once police officers have probable cause to believe that someone is under the influence, they can ask to perform a chemical test. Breath testing can establish a likely blood alcohol concentration (BAC) for the driver who provides the sample. A chemical test result that is over the legal limit only helps strengthen the state’s case.
Thankfully, drivers accused of DUI offenses have the right to assert themselves in court. They can push back on the legality of a traffic stop or provide a medical explanation for why they failed a test. There are many different ways for defense attorneys representing those accused of DUI offenses to undermine the state’s evidence.