A majority of the states that have had the issue raised have found that HGN is admissible to prove intoxication. Some states have rejected it’s use at trial though also. I’ve never, ever seen a case anywhere in the United States, where HGN was the only evidence used at trial to prove impairment. In states that allow the HGN, it is considered circumstatial evidence of the driver’s impairment, and is to be considered by the fact finder, along with all the other evidence, to determine whether the driver was operating while intoxicated.
So far we have talked about 3 ways to test for intoxication: chemical Breathalyzers, HGN testing and linewalking/nosetouching. We have established that a Breathalyzer isn’t required for conviction so we’re left with the remaining two subjective if not inaccurate tests. If the officer testifies that these tests were failed, even the Breathalyzer 0.000 result is not exculpatory (Right?). I don’t see how the HGN or linewalk test can result in conviction if they don’t stand alone as evidence. From what I’ve read here, any one of these three can convict.
I’m not sure where you are going with your whole post but I will try to answer. If the Breathalyzer reading is a 0.00 then there is not going to be a conviction. If there is a blood test then you might prove intoxication with other substances (but lets not go there now or even mention DRE). Neither HGN or any of the other test is used as a stand alone indicator of intoxication and would not lead to a conviction. Yes it is possible to get a conviction without a BAC reading. No you can’t get one with only HGN or only the walk and turn or any other single indicator. Very detailed testimony must be given including all reasons for the arrest. I listed many above and I will not go through it again.
Incorrect HGN is one of the field tests and is considered along with the other physical tests. More accurately impairment is indicated by several factors: actions of the suspect, field tests and other physical indicators such as odor, bladder control etc. BAC is verified by breath test or blood test.
There are a myriad of ways to help prove intoxication in a DUI case. Erratic driving, weaving between lanes, failure to follow traffic laws, smell of alcohol, bloodshoot, watery eyes, unsteady on his feet, slurred speech, disorientation, stand on one leg test, walk and turn test, poor balance, and, yes, HGN. A breathalyzer is not required for conviction, and none of the other evidence is infallible, but taking the totality of the circumstances, they each should be admitted to prove intoxication. A breathalyzer result of 0.000 would certainly be admissible as exculpatory evidence, however, most DUI laws include the possiblility of driving under the influence of pot, coke, or any other impairing drug. How much evidence, however, is necessary to convict is first up to the jury, then the judge, then the appellate court. It’s not a simple yes or no proposition.
Are you suggesting that you could recognize the tell-tale eye movements in a few seconds while the person is blinking? I barely had time to process the command before he was ordering me out of the car. Actually, I was following the light with my head, which was kind of stupid, but his demand and the light came so suddenly it didn’t immediately compute that he was testing my eyes.
No, I wasn’t drunk. I passed the breathalyzer, and considering all the factors (I was well rested, full stomach, a heavy drinker in those days), there’s no reason to think my driving was impaired. They had been directly behind me for many miles and only pulled me over for expired registration (and probably the fact that I was driving an old car in the wealthiest county in California). Unless they were extremely talented actors playing “good cop, bad cop,” the officer who had been questioning me was all ready to let me go when his partner appeared and decided to try to catch me on a DUI. They had observed my driving and the one cop had observed my behavior, and nothing raised suspicions, but my performance for a few seconds with a light in my eyes is evidence I’m drunk? The nice cop seemed annoyed by the whole thing.
My point is that it would be easy to pick about such “expert testimony.”
Chula is picking up on my point. It seems like the system is wide open for abuse. I don’t have any reason to doubt that had the police in my earlier anecdote pulled me over in the dark, I’d have been walking the line and staring at a waving pen tip. They had already pulled me over and searched my car without reason and over my objections. If I mouthed off to them, I’d probably have been taken in for DUI.
Look, we all know abuses happen every day. When I’m put in a potentially abusive situation hinging soley on a PO’s subjective judgement, I need to know every deatil of every method to claw my way out of trouble. The fight for justice is the fight against ignorance.
Okay, this is somewhat of a hijack, but this HGN stuff is pretty interesting. I found this WMV-format video of a nystagmus examination (warning for dial-up users: it’s 1.5MB). It raised a few questions with regards to the HGN test for impairment. Perhaps one of the police officers who has administered the test could enlighten me.
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Is that really the kind of thing that police officers see when a person is intoxicated? The jerking of the person’s eyes (in the video) is really quite obvious.
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Does nystagmus always occur at some point when you look far to the left or right, even if you’re sober? I don’t notice it at all no matter how far to the left or right I force my eyes. On the other hand, I can do it voluntarily pretty easily.
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Is it only alcohol that causes the nystagmus to begin at a smaller angle (less than 45 degrees is what apparently indicates intoxication, right?), or is it any intoxicating substance? A few months ago I got pulled over and was given this test (along with the other two sobriety tests) for no apparent reason; I wasn’t intoxicated and I passed the tests (well, I assume I must have, because they said “Okay, be careful,” and let me go). But I was pretty tired at the time; does sleepiness ever cause people to fail the HGN test?
Loach makes an excellent point on this - such a charge likely would not hold up in front of a jury. In the case I mentioned, we settled for a plea bargain to negligent driving. The driver received all the same penalties as a DUI conviction, without having a DUI on his record.
There is absolutely no doubt that this guy was drunk, and more dangerous a driver than most of the DUIs I’ve had that were twice the legal limit. I stopped him just as he was leaving my city and heading out onto the highway, and I seriously doubt he would have made it safely to the next city 15 miles away.
If the case were handled as a bench trial (with a judge alone acting as trier of fact) then I would be quite confident of a conviction. In front of a jury, however, it would be a toss-up and not worth the risk of losing the case. Just as you did, many jurors might not understand that someone can be drunk while under the legal limit.
That article doesn’t impress me much. First, it’s a paper somebody did for a college class, not a peer reviewed study. Second, the 16% was about the entire battery of tests, not just the HGN. Third, the article even admits that the results were skewed because of the way that it was administered. My favorite was a claim that since the NTSB recommends removing contacts prior to administering the test and 8.4% of Americans wear contacts, then the NTSB’s claim of non-alcohol HGN in only 3-4% of people must be wrong. That conclusion makes absolutely no sense at all!
Again, my reliance on the test is based on over 10 years of practical experience, without a single false positive or false negative. If non-alcohol nystagmus shows up as much as that article would like us to believe, you would think I would have seen it happen at least one time.
Don’t we always? 
First, I would stop that test immediately. There is obvious nystagmus while resting (looking straight ahead). That indicates another cause other than alcohol.
What it showed when the eyes were at “maximum deviation” (looking as far as possible to one side) is exactly what we would see. That is only one of six possible clues, though.
Even if you were drunk, you would not be able to tell that your eyes are twitching like that. It is only apparent to someone watching your eyes.
If you are sober, there is usually absolutely no nystagmus (twitching) even at maximum deviation.
For this test, only alcohol causes the nystagmus that we’re looking for. I understand that some drugs will cause “vertical nystagmus” (caused by looking as far up as possible) but I’m not trained in that test.
That’s fascinating – before I found that video I wasn’t sure what sort of movements you were talking about, but now I understand.
As for the six possible clues, are you referring to overall clues (like alcohol on the breath, slurred words, etc.) or are you specifically talking about eye-movement clues? (Or even just eye clues not limited to movement, like bloodshot eyes?)
Okay, that explains why I couldn’t see any nystagmus in the mirror and my wife couldn’t see any in my eyes – you have to be drunk. (Oddly enough, I could swear I saw her eyes twitching when she was looking all the way to the left or right, even though she never drinks. I guess I must have been mistaken.)
Interesting. I recall reading somewhere … I thought it was in the Straight Dope, but I can’t find the column now, if it was indeed one of Cecil’s columns … that squirting ice water into the ear canal will cause nystagmus. And one of those links above says that nystagmus can be caused by damage to the balance system of the inner ear. I wonder if the reason alcohol causes it is that it causes dizziness? And, if so, can you simulate alcohol-induced nystagmus by whirling around a bit and having somebody watch your eyes?
Just eye movement clues. To be more accurate, there are three clues that we look for in each eye for a total of six. They are: lack of smooth pursuit (how the eye follows a moving object side-to-side), distinct nystagmus at maximum deviation, and onset of nystagmus prior to 45 degrees. If you have any four, that’s an indication (not absolute certainty) that the person’s BAC is over .10.
Actually, she might have a tiny bit of twitching at maximum deviation. But what we’re looking for is that really distinct, obvious nystagmus that you saw on the video.
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samclem’s been a moderator for more than 10 years??? That’s some kind of record, isn’t it?
Drive-by zombie reported.
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That’s why he gets the big bucks.