Police officers are required to have probable cause (a legal reason) before they can make a traffic stop. Once an officer initiates a stop, if he or she suspects a Utah resident of being under the influence, that suspicion must be confirmed before the driver can be arrested. This is why they are supposed to be trained to identify certain behavioral patterns and perform preliminary on site DUI tests.
Just because a driver’s eyes are bloodshot and speech is slurred, does not necessarily mean he or she is impaired. Fatigued individuals may present the same symptoms. Therefore, officers will generally first perform a horizontal gaze nystagmus test, which measures how much the eyes are “bouncing.” Even this may not be conclusive enough for an arrest, so many officers carry a portable breath test device to obtain a preliminary blood alcohol content (BAC) reading. Field sobriety tests such as walking a straight line, saying the ABC’s backwards, and the like may also be performed.
Officers use these tests to establish probable cause for a DUI arrest. However, they do not make good evidence for court. That is why an official breath test — and or a blood test — can only be performed after an arrest.
If you are arrested for DUI in Utah, it is imperative that you engage legal counsel as soon as possible. You are entitled to due process of law, which includes the right to be presumed innocent and to confront the evidence and witnesses against you. Your situation will be reviewed to determine that your rights were protected. If the traffic stop was not legal or the tests were not properly performed, the charges against you might be dismissed.