Criminal Law Blog
August 27, 2006
If you’ve been pulled over and the officer suspected you’d been drinking, you probably had to endure the pen test, or as it is more technically called, the horizontal gaze nystagmus test.
“Nystagmus” means exaggerated bouncing or jerking of the eyeball. It can be caused by many things, but the officer will nearly always assume that whatever nystagmus he sees is caused by alcohol.
The cases and literature indicate that, in addition to alcohol, many other factors have been mentioned as a possible cause of nystagmus. They include: (1) problems with the inner ear labyrinth; (2) irrigating the ears with warm or cold water under peculiar weather conditions; (3) influenza; (4) streptococcus infection;
(5) vertigo; (6) measles; (7) syphilis; (8) arteriosclerosis; (9) muscular dystrophy; (10) multiple sclerosis; (11) Korchaff’s syndrome; (12) brain hemorrhage; (13) epilepsy; (14) hypertension; (15) motion sickness; (16) sunstroke; (17) eye strain; (18) eye muscle fatigue; (19) glaucoma; (20) changes in atmospheric pressure; (21) consumption of excessive amounts of caffeine; (22) excessive exposure to nicotine; (23) aspirin; (24) circadian rhythms; (25) acute trauma to the head; (26) chronic trauma to the head; (27) some prescription drugs, tranquilizers, pain medications, anti-convulsants; (28) barbiturates; (29) disorders of the vestibular apparatus and brain stem; (30) cerebellum dysfunction; (31) heredity; (32) diet; (33) toxins; (34) exposure to solvents, PCBs, dry cleaning fumes, carbon monoxide; (34) extreme chilling; (35) eye muscle imbalance; (36) lesions; (37) continuous movement of the visual field past the eyes, i.e., looking from a moving train; (38) antihistamine use. See Schultz v. State of Maryland, 106 Md. App. 145; 664 A.2d 60 (Md. Ct. Spec. App. 1995).
Police officers are taught that before they begin administering the pen test, they must first make sure that you are a good candidate for the test. To do that, they should ask for a little bit of medical history from you. He should have asked whether you were taking any medications and whether you had suffered any head injuries. They ask about other things, too, but the other questions are intended to “clear” a suspect to take other tests.
The trouble is: the officers aren’t trained to ask anything related to the many other causes of nystagmus. If they see 4 of 6 possible clues, and smell alcohol on your breath, chances are you are going to jail.