Law enforcement officers commonly use roadside sobriety tests to determine if a driver is under the influence of alcohol or drugs. The three most common procedures are the walk-and-turn test, the one-leg stand test and the horizontal-gaze-nystagmus test.
While these gauges may seem sufficiently scientific and objective, several factors make them unreliable.
Subjectivity in interpretation
One major issue is the subjective nature inherent in scoring roadside sobriety tests. Personal biases, such as perceptions about ethnicity, subliminally affect how officers perceive what they see and hear. This may lead to false arrests and unfair legal consequences.
Variability in test conditions
The environments in which these evaluations happen may impact their accuracy. Weather, road surface and lighting all affect the ability to pass. For instance, icy roads or poor visibility due to rain make it difficult for anyone, sober or not, to perform physical feats. It is thus impossible to draw definitive conclusions based solely on performance.
Nervousness and anxiety
Drivers may experience heightened anxiety and stress during a sobriety check. The odds are high that the person undergoing an exam is already dealing with a psychological ailment; nearly one in three American adults will suffer from an anxiety disorder at some point. A roadside test is bound to exacerbate that emotional condition, increasing the chances of the subject committing an error.
Physical and health limitations
Sobriety tests often mandate that individuals perform specific movements. Not everyone can complete these tasks due to existing medical conditions, injuries or disabilities. One could effectively argue that driver checks unfairly target individuals struggling with mobility or other health-related challenges.
The reliability of roadside sobriety tests is anything but bulletproof. Commuters facing a request to undertake one have good reasons for refusing to comply.