There are other flaws with the HGN test result. Chemicals, drugs, and numerous substances can cause nystagmus (jerking of the eyes) without the presence of alcohol.
For example the ingestion of barbiturates, antihistamines, phencyclidine, depressants, and anticonvulsants can cause nystagmus. Other influential substances include caffeine, nicotine or aspirin. Even atmospheric pressure influences nystagmus. [Read more…]