A roadside balance-and-attention exercise used by police to look for signs of alcohol or drug impairment, it asks a person to take heel-to-toe steps in a straight line, turn in a specific way, and walk back while following instructions.

Officers usually watch for specific "clues," such as starting too soon, missing heel-to-toe contact, stepping off the line, using arms for balance, taking the wrong number of steps, or making an improper turn. The test is part of the standardized field sobriety tests developed for DUI investigations, but real-world conditions can affect performance. In Alaska, black ice from September through April, heavy boots, uneven shoulders, fatigue, injuries, and ice fog in Fairbanks can all make a sober person look unsteady. Medical issues involving the back, knees, hips, inner ear, or neurological function can matter too.

That can make the test a major point in a DUI case. An officer may use poor performance to justify an arrest, support probable cause, or help explain why a chemical test was requested. In court, a defense lawyer may challenge whether the instructions were clear, whether the surface was safe, and whether weather, footwear, or a prior injury affected the result. Alaska's main DUI law, AS 28.35.030 (current through 2024), does not require a conviction to rest on this test alone, but walk-and-turn evidence often becomes part of the broader fight over impairment and reliability.