A field sobriety test is a test in which you must perform a series of coordinated activities, such as walking a straight line. Unlike a chemical test, most states consider field tests voluntary, and they may be refused. However, every state except Nevada requires you to submit to a Blood Alcohol Concentration test, such as a breathalyzer test, if requested by a police officer. Failing to do so results in immediate sanctions, such as license suspension. A BAC test can be a blood, urine or breath test. You do not have the right to choose what kind of BAC test you take but must take the test requested by the officer.