How Accurate Are Field Sobriety Tests?

Police officers conduct field sobriety tests when they suspect a driver has been drinking or is otherwise impaired. They test someone’s ability to focus on a task, their balance, and their physical abilities. But, some tests provide more accurate information than others.

Depending on the type of test an officer makes someone do, nerves or naturally poor balance can put their freedom at risk. Here is what drivers need to know about field sobriety tests:

Non-standardized tests

Many of the tests people associate with a DUI stop – like reciting the alphabet backward or touching a finger to your nose – are not actually standardized or widely accepted for their accuracy.

Standardized field sobriety tests (SFST)

The sobriety test endorsed by the National Highway Traffic and Safety Administration consists of three parts:

• Horizontal gaze nystagmus: Checks for involuntary jerking of the eyes when trying to track movement
• Walk and turn: Tests the ability to listen to instructions and follow them, as well as balance
• One-leg stand: Tests balance, which is often impaired by alcohol

Researchers have conducted several studies over the years to determine the accuracy of these tests. The one most often cited, the “San Diego Study” in 1998, found that when all three tests were administered together they were 91% reliable. But, as some North Carolina residents found out while participating in a local news story, it is easy to flunk the test even when sober.

If a field sobriety test is not conducted properly, a North Carolina DWI attorney can help a defendant fight back against criminal charges. Challenging the validity of a sobriety test can lead to having charges reduced, or even dismissed.