As a former prosecutor I used to think field sobriety tests were a golden ticket to conviction. Along with the chemical tests, I had my police officer administering a number of super reliable tests and the results were typically favorable to prosecution. I would look at the police room and boom, boom, boom, I had the defendant sinking his/her own case. It wasn't until a few skilled defense lawyers began taking apart these tests that I soon realized they were not as reliable as I once thought.

In Michigan a witness, typically a police officer is allowed to testify to Standardized Field Sobriety Tests (SFST) results and how they relate to impairment if the witness is qualified by knowledge, skill, experience, training, or education. The law specifically states that the Horizontal Gaze Nystagmus (HGN) is admissible under this provision by an officer trained in how to perform the test.

In Michigan “Standardized Field Sobriety Test” means one of the standardized tests validated by the National Highway Traffic Safety Administration (NHTSA). A field sobriety test is considered a SFST under this section if it is administered in substantial compliance with the standards prescribed by NHTSA.
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In simple terms if the police officer is qualified and follows the rules then the evidence can be introduced to the trier of fact or at a evidence hearing. The problem for many people charged is their attorney simply reads the police report and doesn't look into if these tests were done correctly. A cop is NOT going to say they did them wrong in the report - it takes watching the video and listening to the instructions to confirm compliance.

Based on my experience as a prosecutor, I know that the prosecutor has not watched the video or firmed up these tests; they just assume they are done correctly. This means if I look further into the issue and spot problems, they WILL NOT be prepared to respond at a hearing or trial, and I have a good shot at making a statement in front of a jury or judge and hopefully discredit these tests.

According to a State of Michigan law enforcement memo, the SFSTs are designed as divided attention or psychophysical tests which involve requiring the subject to concentrate on both mental and physical tasks at the same time.

These tests are designed to mimic the different abilities and tasks involved in operating a motor vehicle. These include information processing, short-term memory, judgment and decision making, balance, steady and sure reactions, clear vision, small muscle control and coordination of limbs.

As a criminal attorney, I am only looking for the BIG THREE: HGN, Walk & Turn and One Leg Stand, because any other test is not standardized and a fiction of the officer's imagination. An officer can just as easily as my client to recite the Detroit Tigers lineup as he can the alphabet - I am going to discredit anything outside of the BIG THREE right away.

According to various studies, the HGN is only 77 percent accurate, the Walk and Turn is 68 percent accurate and the One Leg Stand is only 65 percent accurate.

As a prosecutor, I would quickly glance at the officer's narrative and just assume "LOOKS GOOD" and move on. As a criminal defense lawyer, I dig into the details and test the officer narrative to the video/audio. Even a small difference between report and video could mean putting the officer in a position of trying to make his report/narrative more favorable and really discredit the whole process. We get the benefit of the doubt on the things we can't see and hear if what we can see and hear is not 100 percent accurate, and it's so important to make a big stink about it, because a jury doesn't know any better.

The first test is always the most fishy - the HGN, because there is no video or audio of what the officer is actually observing on my client since it's his eyes - I am looking for proper or improper instructions and if I can see how the officer is actually administering the tests. If he does it by the book, I am hoping that his credibility is put into question on another test, which I can see better such as the one leg stand or walk & turn, so I can argue that it simply taints all the tests.

According to the officer training manual here are the proper instructions: ​

1)Please remove your glasses (if worn).
2)Put your feet together, hands at your side. Keep your head still and follow this stimulus with your eyes only.
3)Keep looking at the stimulus until the test is over.
4)Do not move your head.
5)Do you understand the instructions?

The officer will then position the stimulus 12-15 inches from the suspect’s nose and slightly above eye level. He or she will first check to see if both pupils are equal in size (if they aren’t, this may indicate a head injury). The officer will then make sure the eyes are able to track together (called equal tracking) across the suspect’s entire field of vision.

Here the officer is looking to see if the eyes track the stimulus together or if one eye lags behind the other (this would indicate medical disorder, injury or blindness). After this is done, the officer continues with the test as listed below:

The officer is now looking for the three clues in each eye, so 6 total clues.

1) The Lack of Smooth Pursuit –the eyes can be observed to jerk or bounce as they follow a smoothly moving stimulus, such as a finger or penlight. The eyes of an unimpaired person will follow smoothly, i.e., a windshield wiper gliding across a wet windshield; whereas the eyes of an impaired person will follow in a jerking manner, i.e., a windshield wiper moving across a dry windshield.

​a.Instruct the subject to hold their head still and to follow the stimulus with their eyes only. b.Move the stimulus smoothly, all the way to the subject’s left, then all the way to the right, then back again all the way to the left, then once again all the way back to the right.
c.While the eye is moving, examine it for evidence of a lack of smooth pursuit.
​d.Each eye counts as one clue for scoring purposes.

2) Distinct and Sustained Nystagmus at Maximum Deviation –distinct and sustained nystagmus is observed when the eye is held at maximum deviation for a minimum of four seconds. People’s eyes exhibit a slight jerking at maximum deviation even when unimpaired, but this jerking will not last more than a few seconds. In alcohol-impaired individuals, the jerking is larger, more pronounced, sustained for more than four seconds, and easily observable. Nystagmus at maximum deviation is observed when the eye is moved to the point where there is no longer any white left in the side of the eye. The nystagmus can be observed to act in a back and forth “popping” motion.

​a.Position the stimulus as before.

b.Move the stimulus all the way to the subject’s left side and hold it there so that the subject’s eye is turned as far to the side as possible.

c.Hold the eye at that position for a minimum of 4 seconds to check carefully for any jerking that may be present.

d.Then move the stimulus all the way to the subject’s right side and hold it there for a minimum of 4 seconds checking again for any jerking that may be present.

e.Repeat both steps b and d (check each eye twice).

f.A definite, strong jerking must be seen; a slightly or barely visible tremor is not sufficient enough to count as a clue.

g.Each eye counts as one clue for scoring purposes.

3) Onset of Nystagmus Prior to 45 Degrees –the point at which the officer first observes nystagmus or jerkingin the eye. If the jerking begins prior to 45 degrees (typically when the stimulus is aligned with the subject’s shoulder),recent studies have shown that the jerking corresponds with a 0.08-plus BAC. The higher the degree of impairment, the sooner the nystagmus will be observable.

 a.Position the stimulus as before.

b.Slowly move the stimulus to the subject’s left side, carefully watching the eye for the first sign of jerking.

c.When you think that you see the eye jerk, stop moving the stimulus and hold it still.

d.Make sure to verify that the eye is in fact jerking.

e.Once you have established that you have located the point of onset, estimate the angle.

f.Repeat this procedure on the subject’s right eye.
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g.Repeat both steps b and f (check each eye twice).

h.Each eye counts as one clue for scoring purposes.

Next up is the Walk and Turn - officer is looking for 8 clues. Here are the instructions, which I am looking for compliance or non-compliance.

1)Put your left foot on the line, then your right foot on the line ahead of your left. Keep your arms at your side. (Demonstrate)

2)Do not start until I tell you to do so.

3)Do you understand? (Officer must receive an affirmative response)

4)When I tell you to begin, take heel-to-toe steps on the line. (Demonstrate) To turn around, keep one foot on the line and return nine steps.

5)When you turn on the ninth step, keep your front foot on the line and turn taking several small steps with the other foot. (Demonstrate) Take heel-to-toe steps back down the line.

6)Keep your arms at your side at all times, watch your feet, and count each step out loud. Once walking begins, do not stop until you’ve completed the test.

7)Do you understand the instructions?

8)You may begin.

9)If suspect doesn’t understand some part of the instructions, officer should repeat only that part which suspect does not understand.

Here are the 8 clues the officer is looking for during the test.

​1)Can’t balance during instructions

2)Starts too soon Walking Stage clues:

3)Stops while walking

4)Doesn’t touch heel-to-toe

5)Steps off line

6)Uses arms for balance

7)Loses balance on turn or turns incorrectly

8)Takes the wrong number of steps

Officer will be quick to point out which clues he observed, but it's important to point out what he didn't observe. Let's say the officer lists 3-4 of them, well that means you didn't see the other 4-5, which means something.

Finally, we have the one-leg-stand - here are the proper instructions:

1)Stand with your feet together and your arms at your side. (Demonstrate)

2)Maintain position until told otherwise.

3)When I tell you to, I want you to raise one leg (either leg) approximately six inches off the ground, foot pointed out, both legs straight, and look at the elevated foot. Count out loud in the following manner: 1001, 1002, 1003, and so on, until told to stop.

4)Do you understand the instructions? 5)You may begin the test.

The timing is very critical during this test. The original research has shown that many impaired subjects are able to stand on one leg for up to 25 seconds but that few can do so for 30 seconds or more.

The One-Leg-Stand is divided into two phases:
1) Instruction Stage and 2) Balance and Counting Stage.

During the Instruction Stage, the subject must stand with their feet together, keep their arms at their sides, and listen to the instructions.
During the Balance and Counting Stage, the subject must perform and complete the exercise as instructed.

There are 4 clues that an officer is looking for during the OLS exercise.

They are as follows:

1)Sways while balancing
2)Uses arms for balance
3)Hops
4)Puts foot down

Same as the walk and turn, if the officer points out clues he observed, it is important to point out what he didn't see.

These field sobriety tests are so ripe for attack by a defense attorney, but it takes some extra work. Field sobriety test issues can be used to challenge an arrest or can be used to help argue a close call BAC case. A chemical test result can be presumed to be what the driver would have registered while driving, but that assumption is not required. If I have a 0.09 BAC an hour later, but the field sobriety tests are actually pretty good, I can argue the deviation, plus timing, plus rising blood that my client wasn't above the limit while driving. I can also use the field sobriety tests to challenge an arrest, especially if there is no PBT result over the limit.
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The possibilities are endless, you just need to be prepared to look deeper into the issue.

When it comes to public perception of drunk driving cases in Michigan, most people imagine the accused performing the walk and turn on the side of the road.  The walk and turn has become so well known, because it’s used in the media as a way to show someone pulled over and under investigation, and that perception is reality in Michigan; the walk and turn is a major part of an officer’s toolbox for a DUI investigation.  

Like the other field sobriety tests, this test must be properly administered and has two different parts; proper instructions to the participant and the performance stage.  Here are the instructions which must be provided to the participant in order for the test to be properly conducted, and all of them must actually be demonstrated by the officer to the participant.

#1 - Place your left foot on the line (the officer must demonstrate this)
#2 - Place your right foot in front of your left foot, with the heel of your right foot against the toe of your left foot
#3-  Keep your arms down at your sides
#4 - Only begin when told to do so

The officer will then ask the participant if they understand the instructions.  The participant must say YES, if not, the officer must clarify anything asked by the participant.  

If the participant says YES, then the officer will instruct the participant to walk nine steps heel to toe forward, turn while keeping your lead foot on the line, and take several small steps with the other foot before walking back nine heel to toe steps.  Along with these instructions the officer must demonstrate it for the participant.  Along with these steps, the participant must look at their feet, keep their arms down at their sides and count while walking.  

Frankly this is a lot to remember and a stressful situation for the participant.  Despite the odds against the participant to perform this accurately, the NHTSA tells the officer to look for 8 clues for intoxication and/or impairment.  If you show 2 signs, you fail the test according to their rule book.  Here are the 8 clues:

Can’t balance during instructions, starts too soon, stops while walking, fails to touch heel to toe, stepping off the line, uses arms for balance, improper turn and wrong number of steps.  

If the participant can’t perform the test, then you fail all 8 parts.  When I evaluate a field sobriety test as part of a DUI Case, I am looking for an officer who gives incorrect instructions, doesn’t demonstrate the test and orders the wrong amount of steps.  We’re also looking for what the NHTSA manual calls proper conditions.  

If the officer doesn’t do his job properly then the test results lose credibility, and I would use to paint doubt on the prosecution’s entire case.  If there’s one crack, one error, one point of unfairness to my client then the whole case likely has issues. ​

When a client is pulled over by the police or investigated for a DUI at the scene of accident, the police are now in evidence gathering mode.  They are looking for evidence of operation; once they have that, they are then looking for evidence of “being drunk”.  This second bucket of evidence comes from the preliminary breath tests, officer observations, statements by the defendant, and field sobriety tests.  

A lot of attorneys overlook field sobriety tests, and focus on trying to attack the chemical tests.  While it is very important to examine all of your defenses with the chemical tests, the field sobriety tests can be extremely fruitful for a motion to suppress based on an illegal arrest, or assist in a defense at trial.  

When an officer makes the decision to arrest you, it’s a combination of evidence of operation and probable cause that you committed a drunk driving offense.  An officer offers up a PBT test along with numerous field sobriety tests; most people agree to both, which is a mistake.  I’ve already discussed how to beat, and use the PBT in your favor, but field sobriety tests can also be declined.  

Taking a series of field sobriety tests is very unlikely to help your case.  The tests are usually taken at night, in potentially freezing weather with rain or snow falling, on the side of the road with other cars flying by and pressure from an authority figure.  You’re also likely tired and very nervous; it’s like trying to tie your shoes while standing in the middle of a lion’s cage.  

If you don’t take field sobriety tests, and you decline the PBT, then an officer may not have enough to make a legal arrest.  An officer will have to rely on statements about drinking, how you walked, and talked and observations of your eyes, your smells and your demeanor.  If you don’t open your mouth or make admissions then the prosecutor has a thin case for showing a valid arrest.  It’s very possible to move for suppression under these circumstances.  

If my client took field sobriety tests, it’s likely that they “failed” enough to justify an arrest; if a client happened to do very well on the tests then they can help in the argument that the officer lacked probable cause to arrest you, especially if there was not a PBT over the legal limit.  

Field sobriety tests can also assist at trial.  Each test has a set of specific instructions.  If an officer fails to read those instructions properly then the test results should be thrown out.  If an officer misrepresents how my client performed in his police report, because the video shows the client doing better than documented, it could hurt the officer’s credibility on the entire case.  

An officer is trained by the National Highway Traffic Safety Administration, and these standards are available to the public.  I use the same manual to attack the officer’s administration of the tests, and their selection of those tests.  For example, an officer is trained that there are only three field sobriety tests that have been deemed scientifically reliable to detect intoxication/impairment.  
Horizontal Gaze Nystagmus (HGN) is one of three standard field sobriety exercises conducted by law enforcement. This test looks for involuntary jerking of your eyes as you gaze toward the sides.  The other two tests are the walk-and-turn and the one-leg stand.  Any test outside of these three should NOT be used.  If an officer conducts anything else then they are conducting themselves outside of their training, and it opens the door for an attack on multiple fronts.  

Finally, if we’re working with BAC levels that straddle the 0.08 or 0.17 lines for different charges, a strong performance on the field sobriety tests can sway a jury to go with our argument that the BAC reading is inflated, and not accurate as to what it was when my client was driving the car.  Here’s an example.

My client is charged with an OWI.  He is stopped at 2 am by the police.  My client refuses the PBT, but takes field sobriety tests, which he does well on.  The officer admits to him passing most of the tests, and the video backs this up, and even discredits some of the officers observations as being too bearish.  The client has a 0.10 BAC at 3 am.  At this point we have the opportunity to argue rising blood.  

The theory goes: look how well the client did on the field sobriety tests - that doesn’t look like someone over the legal limit.  Yes he blew a 0.10 an hour later, but he had just finished drinks before getting in his car, and when driving he was below 0.08, and it only rose to 0.10 after time has passed.  This technique requires some well planned cross-examination of the police officers, and potentially the Michigan State Police representative or an expert witness brought in by the defense. ​