Here in Utah, prosecutors have two options in their attempts to secure a conviction for driving under the influence. The first is to provide the court with conclusive proof that a driver's blood alcohol level was above the state's legal limit of .08. Failing that, a DUI conviction could only be obtained by proving beyond a reasonable doubt that the driver was unable to operate his or her vehicle safely.
Proving that someone was not able to drive safely is difficult, which is why law enforcement officials rely on breath and blood tests to prove intoxication. During a traffic stop, officers will most likely not warn you that you are not required to submit to a portable breath test or field sobriety tests -- especially if you have not been placed under arrest. You are also not required to speak to the officer or officers.
The situation changes somewhat if the officer places you under arrest. You can still refuse to submit to the portable breath test and/or a Breathalyzer test. However, this puts you at risk of having your driver's license suspended. Moreover, you may still be charged with driving under the influence. Having an attorney represent your rights and interests for both the possible license suspension and the DUI charges would be beneficial since proof of wrongdoing on your part will be difficult for Utah prosecutors without evidence.
Without a breath test taken at the time of the traffic stop, no concrete evidence of intoxication exists. It becomes a matter of the officer's observations, which might not be enough to legally substantiate a DUI charge. Understanding your rights and responsibilities regarding taking a breath test or participating in field sobriety tests during a traffic stop gives you the option of protecting yourself since you are not afforded the right to an attorney at that time.