The walk and turn test is a standardized field sobriety test (SFST) used by law enforcement officials to determine if a driver is under the influence of alcohol and/or drugs. This test is one of the most commonly used field sobriety tests and is recognized by the National Highway_traffic Safety Administration (NHTSA) as one of three standardized field sobriety tests. The walk and turn test has been scientifically validated as an indicator for alcohol influence, which means that if a driver fails this test, it can be used to establish probable cause for an arrest for driving under the influence.
During the walk and turn test, the driver is asked to walk in a straight line, heel-to-toe, for approximately nine steps, then turn around and walk back to the starting point in the same manner. The NHTSA has established specific conditions for this test to be performed properly:
Surface Settings: The test must be conducted on a reasonably dry, hard, level, non-slippery surface.
Demarcation Settings: A straight line must be present for the driver to follow, or a line can be drawn in the dirt or on the sidewalk with chalk.
Light Settings: Adequate lighting must be available for the test to be conducted successfully.
The test is divided into two phases, an instructional phase and a walking phase. During the instructional phase, officers are looking for two or more clues of impairment. These clues include:
-
Balance While Following Instructions: The driver is unable to maintain a heel-to-toe position while listening to the instructions.
-
Starting Before Instructions Are Completed: The driver begins walking before all instructions have been given.
-
Stopping While Walking to Steady: After one step, the driver pauses for several seconds.
-
Failing to Touch Heel-to-Toe: The driver leaves a space of one-half inch or more between the heel and toe on any step.
-
Stepping Off the Line: The driver steps so that one foot is entirely off the line.
-
Using Arms for Balance: The driver raises one or both arms more than six inches from their sides.
-
Losing Balance While Turning: The driver removes the pivot foot from the line while turning.
-
Incorrect Number of Steps: The driver takes either more or less than nine steps in each direction.
During the walking phase, officers are looking for:
-
Proper Turn: The driver turns properly by taking a series of small steps with the other foot.
-
Keeping Count: The driver counts their steps aloud.
-
Walking in a Straight Line: The driver maintains a straight path and steps on the line.
After completing the walk and turn test, officers will assess the driver's performance and assign a score based on the number of clues of impairment they observed. A score of two or more clues indicates that the driver's blood alcohol concentration (BAC) is likely above 0.08 grams per deciliter (g/dL).
It's important to note that the walk and turn test is not without its challenges and can be influenced by various factors such as:
1.警官的错误：警官在演示测试或解释线索时可能会出现错误，导致驾驶员的表现受到影响。
2.健康状况：某些健康状况，如焦虑或神经系统疾病，可能会影响驾驶员的表现。
3.环境条件：噪音、天气状况或其他外部干扰可能会导致驾驶员注意力分散，从而影响他们的表现。
4.服装问题：穿着不合适的鞋子或衣物可能会限制驾驶员的活动能力，影响测试结果。
Despite these potential limitations, the walk and turn test remains a crucial aspect of many drunk driving investigations. It provides law enforcement officers with a reliable indicator of a driver's level of impairment and can help secureprobable cause for an arrest. As with any field sobriety test, itsresults must be interpreted and evaluated in the context of the overall circumstances and in conjunction with other evidence.