Like checking whether someone can balance on one foot while pulling on a boot, this exercise measures balance, coordination, and the ability to follow simple instructions at the same time. In legal use, the one leg stand test is a roadside field sobriety test used by police during a DUI investigation. The person is usually told to raise one foot about 6 inches off the ground, keep both legs straight, look at the raised foot, and count out loud for 30 seconds. Under the National Highway Traffic Safety Administration protocol, officers look for four standardized clues: swaying, using arms for balance, hopping, or putting the foot down.

The test matters because it is often used to support probable cause for an arrest. It does not directly measure blood alcohol concentration, and poor performance can be caused by fatigue, ice, uneven pavement, cold exposure, injury, age, footwear, or a medical condition affecting balance. Those limits can become part of a defense challenge.

In Alaska, the one leg stand test is commonly used in investigations under AS 28.35.030, the state's DUI statute. Alaska's implied consent law, AS 28.35.031, applies to chemical testing, not roadside balance tests. That means refusing a one leg stand test is not the same offense as refusing a post-arrest chemical test under AS 28.35.032. After a crash, an officer's observations during this test can also affect fault arguments and the value of an injury claim.