If you get pulled over and an officer wishes to conduct an investigation regarding a possible DWI (DUI) you are not required to do field sobriety tests prior to arrest. Any pre-arrest tests you may be asked to take are not mandatory. You will not lose your license for refusing any such tests. The requirement to take a field sobriety or blood alcohol test only applies after you are arrested. If you refuse at that time, the State will seek to suspend your license. You are also not required to answer any questions regarding your activities. Prior to arrest, a driver is generally only required to provide license and registration.
In asking questions and requesting field sobriety or other testing, an officer is gathering information to determine if there is probable cause for an arrest. By answering questions or performing tests, you are assisting the officer in developing probable cause. It would be difficult for an officer to gather sufficient evidence for an arrest if the only observations that officer had were of you sitting in the vehicle.
Often the officer will ask the operator to step out of the vehicle. If you are going to be placed into custody an officer can order you out of the vehicle. (Custody usually, but not always, leads to an arrest). Ask the officer if you are being ordered out of the vehicle. If you are ordered out of the vehicle, comply with the officer’s order. The time to challenge the officer’s decision to place you in custody is not as it is happening. A failure to comply can lead to additional charges. If the officer has not developed probable cause to arrest you, a motion to dismiss those charges can be filed.
If the officer cannot develop probable cause to arrest the vehicle can still be towed and the driver placed into protective custody. But that custody ends without any charges and as soon as the driver is released to a sober individual.