Most people believe that if you pass a field sobriety test, the officer must let you leave. This is not always the case. Many State laws allow police officers the right to increase the number of tests, hoping that you will fail one. Even after successfully performing field sobriety tests, you may still be arrested.
Consider the case of David Bell of Tennessee. David Bell had been drinking earlier in the evening and did smell of alcohol. He was pulled over for going the wrong way down a street. David was asked to perform not just one but six field sobriety tests. Even after passing all tests, the officer still felt that David Bell was unsafe and placed him under arrest. After arresting David Bell, the officer obtained a blood sample and David was charged with DUI.
David's Lawyer used a motion to suppress the blood sample evidence. the lawyer was able to use the video from the patrol car to show the judge that the tests were passed satisfactorily. The lawyer was able to show that the red and blue lights were still on, which is a known cause of failed sobriety tests. On cross examination, the lawyer was able to use the officer's poor recollection of David's field sobriety tests in his favor.
In the end, the judge ruled that David was a victim of an unlawful arrest, and to suppress the blood evidence, calling it the "fruit of the poisonous tree." David's decision to hire the best attorney for DUI may have saved his reputation, and his criminal record.