There are two tests police use in drunk-driving cases. The field sobriety test is performed before an arrest at the scene of the stop itself or somewhere nearby. It includes the famous "walk and turn" among other tests. It is not required. Refusing the field sobriety test will not trigger a driver's license suspension but the refusal could be brought up at trial. If the police believe they have probable cause to make an arrest, they will arrest you and take you to the police station. At that time, you will be asked to submit to a chemical alcohol test which could be breath, blood or urine. Refusing or failing a chemical test will cause a driver's license suspension, which could be challenged in an administrative hearing at DMV.