Nick's Blog

Personal opinions. Aggressively stated.

Watch my Finger

The last three days of the academy are to be spent doing standardized field sobriety testing – SFST. Of course, there’s a practical examination. “If you don’t do every one of the three tests perfectly, you fail SFST, and you fail the academy,” said one of our three instructors. “And there’s a written test – you have to pass that with at least an 80%. That’s why they do this right before the final – so that if you don’t pass this you don’t graduate. There have been some who have come this far only to fail, so study hard.”

Awesome! Thanks.

We’ve all seen it in the movies, and maybe you’re one of the unlucky ones who’ve been pulled over and asked to play in the game of “Follow my finger” or “walk this way”. I personally never have been invited, so I was really at a loss to know what to expect.

Seems that the levels of drunk driving accidents in the 1960s and 1970s led to, it’s said, more than 50,00 fatalities per year, according to the National Highway Traffic Safety Administration (NHTSA, pronounced “Nitsa”). In 1975, NHTSA began funding research into the best ways to enforce the laws against driving under the influence, which followed two tracks: detecting signs of impairment in how people are driving, and running tests to determine objectively whether someone was drunk. Up till then, cops could pretty much make up their own test (“Say the alphabet backwards … in Polish!”).

NHTSA researchers as well as others around the world looking at the issue (including researchers in boozy Finland, compared to which country everyone else in the entire world is at one, large, happy AA meeting) closed in on one test which seemed to be a dead lock: Horizontal Gaze Nystagmus.

When you’ve been drinking, your eyeballs can’t track properly, and there is an involuntary jerking of your eyes as you try to. That jerking is called Nystagmus. Horizontal Gaze Nystagmus is a Nystagmus that occurs as your eyes track an object horizontally from the left or right.

Our instructor has likened this to window wipers on a car: when you’re sober it’s like your windshield when it’s raining – the blades move back and forth smoothly over the surface of the glass. But when you’re totsed, it’s like turning on the wipers on a dry, dusty day – the blades skitter over the surface, getting momentarily stuck then breaking free, repeatedly, across their arc.

The Horizontal Gaze Nystagmus, or HGN test was found in a number of studies to be reliably predictive of a blood alcohol concentration of 0.10% or greater. Later, as the need to detect BAC of 0.08% or even less arose (as tolerance for drunk-driving decreased) NHTSA determined that three tests – HGN, the Walk and Turn and the One Leg Stand – could be combined to result in highly accurate predictive tests when performed in a standardized fashion.

By 1998, NHTSA found that the combined battery of tests produced the right decision by officers to arrest on charges of DWI in 91% of the cases. HGN alone is clearly the most reliable of the tests – it alone produces 88% “right decisions”. But the bonus is that, since the rise of in-car video and audio recordings of officers, not only do we get to see drunk people doing funny stuff, we get to hear them trying to do the tests. The more tests we do, the more evidence we have to play on tape in court, when they try to claim that they were sober as a judge that night.

According to NHTSA, their SFSTs are the standard pre-arrest procedure for evaluating DWI in most law enforcement agencies; they’re used in all 50 states.

Over the next three days, we’d learn the tests themselves, we’d watch them performed, we’d perform them on each other. On day two, five people would come in – friends or relatives of cadets – at noon, having not eaten since breakfast. They’d be dosed with alcohol by one of our instructors, and after 2-1/2 hours of drinking cheap rotgut law-enforcement agency quality hootch (Highland Mist, anyone?) and dining on Sam’s Club nachos and salsa, they’d be hauled out to take the SFSTs that we would administer.

“Now, when you invite your friends to participate,” said Instructor Axton, “Remember something: this is a PO-lice training environment. There are actual PO-lice officers present at all times. If you behave like an ass, you’re gonna get locked up for public intoxication. Why do I remind you of this? Because last time we had some clown who wouldn’t stop bein’ an ass, and I had to call over the campus cops, and they’re like how do you know he’s drunk and I’m like, ‘Cause I dosed ‘im, he’s a point one-two.’ And he went to jail for PI.”


For the rest of the day we tried to memorize the HGN procedures. Basically you’re looking right into the eyes of the person, trying to get them to watch your finger or an object move left and right moving only their eyes, not their head. You ensure that the pupils are equally sized, and then you’re looking for a lack of smooth pursuit (jitters as they follow your finger); a distinct and sustained Nystagmus at maximum deviation (jitters as they look at an object far to their left or right), and the onset of Nystagmus prior to 45 degrees (or jerkiness before the object has traveled a distance from the person’s nose to less than 45 degrees to the right or left.

Around lunchtime, I’m walking back in and there’s this guy in the hallway who’s acting like kind of a dick – I’ve explained how we cadets must stand at attention against the wall when a non cadet is in the hallway. This guy was acting all put out by our standing at attention, as if we were inconveniencing him by doing it. Genesee pulls me over to the side.

“Hey, so you see that guy? Acting like we’re giving him a problem by standing at attention? Well yesterday he did that to me and I’m like, ‘What an asshole. Unreal. Two minutes later Lt America walks up to me with the guy and says to me, ‘Hey, have you met my brother?'”

Back in class, they’ve taught us another trick, useful when someone is very hammered, which is vertical gaze Nystagmus – this is jerkiness in the eyes when tracking an object vertically.

That night I went over to Arnold’s house for about two hours and we studied the jargon and ran tests on each other before calling it a night.

Neither of us was drunk.

Two more days.

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