Cross-Examination on Horizontal Gaze Nystagmus in a Drunk Driving Case

Attorney - Sergeant, assume in a given case that you've got an angle of onset before 45 degrees.
Officer - Okay.

Attorney - What does that tell you?
Officer - The subject is probably under the influence of alcohol.

Attorney - Where does the 45 degrees figure come from?
Officer - I don't know.

Attorney - Please feel free to refer to the manual at any time, Sergeant, but aren't there two reasons?
Officer - That sounds familiar.

Attorney - Isn't the first reason that 45 degrees is close to the angle of onset for a person with a .10 percent blood-alcohol concentration?
Officer - Again, that sounds familiar.

Attorney - And what is the second reason for using the nystagmus field sobriety test to determine intoxication?
Officer - I don't recall.

Attorney - (Reading from manual) "...and because it is easy to estimate." Is that correct, Sergeant?
Officer - That's what it says.

Attorney - You mean, nystagmus is used to test for intoxication because it's only close—to how an average person's eyes will react?
Officer - Apparently.

Attorney - And because it's easy for the police?
Officer - Apparently.

Attorney - Sergeant, does the report indicate a third reason for using nystagmus?
Officer - A third reason?

Attorney - Does it say the test should be used because it's accurate?
Officer - Apparently not.

Attorney - Sergeant, do you consider nystagmus an accurate test of intoxication?
Officer - I think it's fairly accurate, yes.

Attorney - But the state of Kansas has not approved it as a blood-alcohol test,have they?
Officer - A blood-alcohol test? No.

Attorney - You've read an article concerning a study of the accuracy of nystagmus, reported in 25 Journal of the Forensic Society 476 (1985)?
Officer - I believe that's one of the things you mailed me.

Attorney - The study was conducted by a law enforcement agency—the Santa Clara County Criminalistics Laboratory, in California?
Officer - I believe so.

California DUI Laws Drunk Driving Punishment San Diego Courts, Prosecutors and Police Finding A Good DUI Attorney Driver's License Suspensions Field Sobriety Tests Slurred Speech Miranda Advisements Estimating Blood Alcohol Levels Car Insurance After a DUI Alcohol Breathalyzer Tests The Field Sobriety Eye Test What is "Driving" Electronic Home Detention DUI Search Help Home

Copyright 2001 - 2008

Site Map | Legal Disclaimer

Attorney - They analyzed 129 actual cases where nystagmus was given—and compared them with actual BACs, right?
Officer - I believe so.

Attorney - What were the results of that study?
Officer - I believe there was some discrepancy.

Attorney - The officers consistently erred in estimating BAC, correct?
Officer - There was some error.

Attorney - What was the conclusion reached by these researchers, Sergeant?
Officer - They felt there were potential problems with nystagmus.

Attorney - In fact, didn't they conclude that nystagmus cannot be used to predict accurately the blood-alcohol level of a suspect?
Officer - Something like that, yes.

Attorney - You've read ''Psychophysical Tests for DUI Arrest'' by Tharp, a study commissioned by NHTSA?
Officer - Again, counselor, I believe you mailed it to me.

Attorney - Well, didn't that study conclude that some individuals with no alcohol in their systems demonstrated early onset of nystagmus?
Officer - I believe so.

Attorney - In other words, the nystagmus test showed perfectly sober people to be intoxicated?
Officer - Apparently it can happen in isolated instances.

Administration of Test
(Note: The officer demonstrate exactly how he administered the nystagmus test to the client in field.)

Attorney - In the demonstration you just gave, I notice that you didn't ask my client if he was wearing contact lenses?
Officer - It must have slipped my mind.

Attorney - In the NHTSA report, didn't it say that contacts can limit lateral eye movement, causing nystagmus?
Officer - That's correct.

Attorney - What type of template did you use in measuring the angle of onset?
Officer - I didn't use a template. No one in the highway patrol uses one.

Attorney - You did not use a template? Well, what kind of device did you use to measure the angle of onset?
Officer - None.

Attorney - None? You simply guessed what the angle was?
Officer - I didn't guess, counselor, I estimated. It was an estimate based upon extensive training and practice.

Attorney - You used protractors to check your accuracy during this training, didn't you?
Officer - Yes.

Attorney - But you didn't use one that night with my client?
Officer - As I said, I don't ever use one, nor does anyone else on the patrol.

Attorney - Sergeant, if we performed a little test right here in the courtroom, do you think you could detect the difference between 38 and 39 degrees?
Officer - I... maybe not.

Attorney - 42 and 44 degrees?
Officer - Maybe, I'm not sure.

Attorney - The accuracy of this test depends entirely on your ability to... estimate?
Officer - Of course.

Attorney - Well, when was the last time you had your accuracy checked?
Officer - Checked?

Attorney - Yes. How often do you get your ability to estimate angles checked for accuracy?
Officer - I'm not aware of any such procedure.

Attorney - Directing your attention to the NHTSA manual again, Sergeant...
Officer - Yes?

Attorney - Don't these federal reliability standards recommend monthly checks with a template to maintain accuracy in estimating the angle of onset?
Officer - I don't recall reading that.

Attorney - Would you like a moment to review the report?
Officer - No, I'm sure it's in there.

Attorney - Do you agree with the recommendation of monthly checks for accuracy?
Officer - I really don't think it's necessary.

Attorney - Are you saying you disagree with the national experts? Or are you saying that your accuracy doesn't need periodic checks?
Officer - I... just don't think it's necessary.

Attorney - You would agree that the accuracy of guessing the angle is critical to the validity of the test results?
Officer - Estimating, counselor, not guessing. And, yes, I would agree. The results depend on the estimate of the angle.

Attorney - As the computer people say, "Garbage in, garbage out," right?
Officer - Yes.

Attorney - Incidentally, Sergeant, do we have any evidence of the angle in this case?
Officer - Evidence?

Attorney - Yes. Besides your testimony: Do we have any corroboration of what the angle was?
Officer - Corroboration...

Attorney - Is there a videotape? Another witness?
Officer - No, of course not.

Attorney - I see. Then this nystagmus test depends entirely on your accuracy...
Officer - Yes.

Attorney - ...and, of course, on your honesty?
(The attorney has him demonstrate the test again.)

Attorney - I notice that you're holding the pen level with the eyes? And about six inches away?
Officer - That's contrary to the procedure recommended by NHTSA, isn't it? Officer - It's how I was trained.

Attorney - (Reading) "The first movement in each direction should be slow.... The second movement should be somewhat faster." Uh-huh.

Attorney - How many degrees per second do you move the pen during the test, Sergeant?
Officer - Degrees per second? I don't do it that way.