The police may arrest you even though you have a BAC of less than .08. When police decide to make an arrest for DWI they do so as a result of the evidence they have that you are driving impaired. Police make this determination by administering field sobriety tests and observing your behavior. If an officer believes there is probable cause to arrest you he will. This does not necessarily mean you will end up with a conviction of DWI but you can still be arrested.
It is generally advisable to always refuse to complete field sobriety testing if asked to do so. Also do not answer any questions the police may ask you about what you have had to drink, where you are coming from, etc. You have the right to refuse this and will not face any penalties for doing so. Not only does it make less likely the police will have probable cause to arrest, but even if they do arrest you there will not be much evidence that could be used against you.
