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DWI Field Sobriety Tests

When are field sobriety tests used?

In Minnesota, field sobriety tests are used by police officers to determine whether a driver is intoxicated and impaired by alcohol.  Usually, these tests are performed after a traffic stop if the police officer suspects someone of drunk driving but if the officer doesn’t have enough evidence to arrest.

What field sobriety tests are used?

There are a number of field sobriety tests that police officers use to assist them to determine alcohol impairment.  However, many of these tests provide poor accuracy and reliability.  Failure to properly perform the tests may indicate alcohol impairment or any other deficiency (such as poor balance or fatigue).  In addition, even someone with a high BAC could successfully pass the tests despite exhibiting impairment in other ways.  So, these tests are usually used as an initial indication of impairment and more accurate  and reliable tests may be used later to determine the BAC of the driver.

One-legged Stand

This test requires the driver to stand on one leg and balance for 30 to 60 seconds.  The officer will note any problems balancing, including swaying and putting a foot down before the whole duration.  The officer will usually require the driver to count to 30 and will also note if the driver has difficulty counting or misses any numbers.  Although this test might indicate drunk driving, it is mostly and indication of the driver’s general balance — someone with good balance in good conditions will generally do well while someone with poor balance in bad conditions will do poorly regardless of alcohol consumption.

Horizontal Gaze Nystagmus

For this test, the officer holds a light or pen in front of the driver and asks them to track the object with both eyes.  The officer looks for shaking of the pupils, or nystagmus, before the eyes reach 45 degrees.  Police officers generally state that greater shaking indicates greater impairment.  However, police officers generally do not use exact measurements for the amount of shaking and for the angle at which it occurs.  In addition, other factors may cause nystagmus including fatigue and irritation of the eyes.

Heel-to-Toe Walk and Turn

For this test, the police officer directs the driver to walk in a straight line touching toe to heel with each step.  At the end of the line, the driver should turn and walk back.  The police officer looks for ability to comply with instructions and the balance of the driver.  Wobbling, swaying, or failing to touch toes to heels will usually result in a failure.  However, like the other tests, general poor balance, fatigue, and roadside conditions could also result in difficulty with this test.

Other Tests

In addition to the three tests described, many other tests are used, including saying the alphabet backwards and touching fingertips to one’s nose.  However, all field sobriety tests lack accuracy and reliability and may not be sufficient to result in a DWI conviction.  If you are facing DWI or drunk driving charges, you should contact an attorney to learn about defenses to failed field sobriety tests.

Eric Rice is a Minnesota DWI defense attorney who has experience defending against DWI charges.  He offers free consultations to learn about your options and can be reached at (651) 998-9660 or