At what angle of onset for HGN would be most consistent with a BAC of 0.15%?

The angle of onset for Horizontal Gaze Nystagmus (HGN) is an important indicator when assessing an individual for signs of impairment due to alcohol. A Blood Alcohol Concentration (BAC) of 0.15% typically reflects significant impairment, and the onset of HGN becomes more pronounced at greater angles.

At a BAC of 0.15%, the onset of HGN is expected to occur at an angle of approximately 35 degrees. This level indicates that the person has lost a significant degree of eye control, which is consistent with that level of alcohol impairment. Research and training in drug recognition suggest that higher BAC levels correlate with earlier onset angles of nystagmus during the HGN test.

This understanding helps law enforcement and drug recognition experts assess the degree of impairment effectively. While there are other angles listed, 35 degrees is the most aligned with the expected physiological responses at a BAC of 0.15%.