A staple of police assessments of whether a driver is alcohol intoxicated are field sobriety tests. If the officer's interaction with a driver during a traffic stop leads the officer to conclude that the driver is drunk, he or she will likely have the driver exit the vehicle to perform a battery of these tests.
But how reliable are such tests as evidence of intoxication? To begin with, they are not measurable, like a breathalyzer result, and are only useful as indicia of intoxication. On top of that, if the officer makes a mistake while either instructing the subject on how to perform a test or in administering it, such an error can lead to reasonable doubt in the minds of the jury about the validity not only of the tests but also of the officer's overall judgment about the defendant's degree of intoxication.
Field sobriety tests may look easy for police officers to give when watching an episode of "Cops", but actually they must be carefully administered and are subject to a multitude of precise requirements established by the National Highway Transportation Safety Administration.
Take, for example, the "horizontal gaze nystagmus" test, which requires the subject track an object from side to side with his eyes. Simple, right? But if the NHTSA requirements are not carefully adhered to, ranging from how far from the subject's nose the stimulus object should be held, how quickly the officer should move it, and the time that it should take to properly administer, then the police officer may be making mistakes that will reduce if not eliminate its diagnostic or evidentiary value.
Chances are, if you have been subjected to field sobriety tests you will not know whether the police officer is administering them correctly. And if your defense attorney is not well acquainted with the NHTSA guidelines for these tests, then your lawyer may not know, either.
An experienced Missouri DUI defense attorney knows that to maximize the chances of a successful trial defense every possible avenue of raising reasonable doubt must be carefully explored, starting with the basis for the officer's decision to stop the vehicle, the diagnostic procedures he or she used to decide to make an arrest, the chain of evidentiary custody, and more. Leaving opportunities unexplored is something that you cannot afford from your lawyer when your personal freedom and your driving privileges are at stake.