A roadside set of physical and mental tasks used to help an officer judge whether a person may be impaired.

"Field" means it is usually done where the stop happens, not in a clinic or lab. "Sobriety" points to suspected alcohol or drug impairment. "Test" can sound scientific, but these exercises are really observation tools. Common examples include following an object with the eyes, walking heel-to-toe, standing on one leg, counting, or answering simple instructions. Officers look for balance problems, divided-attention mistakes, slurred speech, confusion, and trouble following directions. Medical issues, fatigue, weather, uneven gravel, boots, age, or injuries can also affect performance, which is one reason these tests can be challenged.

In practice, a field sobriety test often helps an officer decide whether there is probable cause for a DUI arrest. It is different from a breath test or blood test, which measure alcohol or drugs more directly. In Alaska, chemical testing after a lawful DUI arrest is tied to the state's implied consent law, Alaska Stat. § 28.35.031. Field sobriety tests may still become key evidence, but they are only one part of the case.

After a crash, poor performance on a field sobriety test can affect both a criminal DUI case and an injury claim. It may be used to argue negligence, support punitive-style damages arguments where allowed, or influence settlement value if impairment is alleged.