Field Sobriety Tests and the Breathalyzer

Field Sobriety Tests

If you have a few drinks before hopping in your car or vehicle to go home for the night, you may be putting yourself in danger of being pulled over for drunk driving. When a cop stops a suspected inebriated driver, he or she may choose to administer field sobriety tests in order to estimate your blood alcohol content (BAC) level. 

There are a number of different examinations that a police officer may give a supposed intoxicated driver. There are three standardized field sobriety tests, which have been established by the National Highway Traffic and Safety Administration, but a number of other non-standardized tests exist as well. Most states also allow officers to request that driver submit to breathalyzer tests.

Standardized Field Sobriety Tests

There are three standardized field sobriety tests that judge a driver’s physical, mental and cognitive abilities. While these exams do not provide number values of BAC levels, they have proven to be highly effective, when administered in combination with one another. The tests include the following:

· Horizontal gaze nystagmus test, which tests the reaction capabilities of one’s eyes

· Walk and turn, which tests one’s ability to follow instructions, balance and coordinate the body

· One-leg stand, which tests one’s balancing, mental and cognitive abilities

Approximately 91% of the time, those who fail a combination of these tests have a BAC level above the legal limit of 0.08%

Other Sobriety Tests

A number of non-standard sobriety tests exist, as well. Some of the more common ones include the following:

· Reciting the alphabet, either forward or backward

· Counting backwards

· Rhomberg stationary balance test

· Closing the eyes and touching the tip of the nose with a finger

· Count the number of fingers the officer puts up

· Put one’s feet together, tilt the head back, and maintain balance

Even though these tests have not been approved by the National Highway Traffic and Safety Administration, officers may choose to use them in the field anyway.


Breathalyzer tests take a breath sample from the suspected drunk driver and perform a chemical analysis in order to estimate the individual’s BAC level. In many states, including Washington, a police officer may request a breathalyzer test from a vehicle operator who may be intoxicated. 

Because these tests are not chemical blood samples, however, many times they are not quite accurate.

Contact Us

If you would like to learn more about field sobriety tests or if you have been charged with DUI in Washington, then the Seattle DUI defense lawyers of Cowan, Kirk & Gaston can help. Visit to learn more.