At what Blood Alcohol Concentration (BAC) level does HGN support arrest decisions?

The correct answer is based on established guidelines regarding the reliability of the Horizontal Gaze Nystagmus (HGN) test as an indicator of impairment due to alcohol consumption. A Blood Alcohol Concentration (BAC) level of 0.08 is significant because it is the legal limit in many jurisdictions for driving under the influence. At this level, individuals are often exhibiting clear signs of impairment, which the HGN test is particularly effective at identifying.

Research has shown that at a BAC of 0.08 or higher, a significant percentage of individuals will display pronounced nystagmus, making it a key factor for law enforcement officers to justify an arrest decision. The HGN test involves observing the eyes for involuntary jerking, which increases as impairment rises, providing the officer with visual indicators that support an arrest for driving under the influence when BAC is at or above this threshold.