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. ​

Along with the HGN test, the next most popular field sobriety test in Michigan is the one-leg-stand.  Like the HGN, the test must be properly administered in order for it mean anything for the prosecution, and as a piece to the puzzle of deciding intoxication and/or impairment.  

If the defense does not properly evaluate and challenge the procedure and the instructions then it doesn’t matter, because the results are the only thing that a judge or jury will see.  

The instructions for the one-leg-stand are very specific and listed in the National Highway Traffic Safety Administration (NHTSA) manual.  Here are the instructions, which must be adhered to for a proper test:

#1 -     Stand straight and put your feet together
#2 -    Keep your arms at your side
#3 -    Stay this way until told otherwise

At this point the officer must ask the participant if they understand.  If the participant says they understand then the officer will continue:

#4 - Please raise one leg, it can be either leg
#5 - Keep your leg 6 inches off the ground, and point your foot out
#6 - Keep both of your legs straight and your eyes on the elevated foot
#7 - The officer will then have the participant count 1001, 1002, 1003 and so forth until told to stop.
The officer should administer this entire instructional and balancing/counting in thirty seconds.  The NHTSA manual instructs the officer to look for the following clues for impairment:
If the participant sways, uses arms to balance, hops and/or puts his/her foot down.  If the participant can’t perform the test, then you’re marked down for showing signs of all four.  
Most of the time, the officer doesn’t administer this test correctly.  The conditions of the road may not match what is required (flat/even surface among others), he may not have given the proper instructions or used the proper thirty second timeframe.  
Most defense attorneys do not even bother to review the videos and scrutinize the officer reports enough to actually realize this, and if they do, they need to know what to do with it.  
Like the HGN, a false positive test may not be the smoking gun, but it is piece of the puzzle of shining light on the prosecution’s inconsistent and questionable case.  If the defense can show that a few of the field sobriety tests are not reliable, and can show any cracks in the officer’s credibility who improperly administered the exams, then it’s a big win for giving the jury something to hold their hat on when it comes to finding reasonable doubt.  ​

One of the most common field sobriety tests requested by police officers in Michigan is the NGN test.  Nystagmus is an involuntary twitching of the eyes.  When an officer checks your eyes, he is looking for this switching.  The officer is looking for distinct Nystagmus at the maximum deviation, a lack of smooth pursuit and the onset of the Nystagmus prior to 45 degrees.   The proper methods for administering the HGN test is laid out in detail in the National Highway Traffic Safety Administration (NHTSA) manual.  

Along with best one of the most popular tests offered, many officers and prosecutors believe this test to be the holy grail of field sobriety tests.  While the test does have some scientific importance, the test is only reliable if conducted properly.  When I review the police reports and videos in a DUI case, I am looking to make sure the officer followed all of the proper instructions and all precautions were taken to have a fair test for my client.  

The test begins with the officer instructing the client to put their feet together, and keep their hands to their side.  The officer will then instruct the client follow a finger, pen or other device with your eyes, and making sure to keep your head from moving.   It’s important to make sure that the officer has asked the client about contact lenses, and any other medical conditions that might be relevant.

Before examining your eyes for the three above factors, the officer should be checking for equal tracking and to make sure your pupils are of the same size; failure to do so, and failure to properly ask about contact lenses could deem the results unreliable.  

The officer checks for equal tracking by starting at the nose, and going right then back to the center then left.  Without this initial check, the rest of the exam is worthless.  

Once the officer has conducted this trial run, he is now looking for smooth pursuit, and looking to see if there is involuntary jerking of the eyes as the object goes from side to side; this is supposed to be two full passes.  The officer then looks for Nystagmus at maximum deviation meaning that there is no white visible at the outside of the eye; it requires the officer to hold your eye at maximum deviation for at least 4 seconds, or the results could be unreliable.  

Finally, the officer will now look for onset of Nystagmus prior to 45 degrees, and vertical Nystagmus.  The first requires the officer to bring the eye out from the middle slowly, and to look for the angle of the onset to see if it’s prior to 45 degrees.  The second requires the officer to move your eye vertically, and to evaluate the onset of Nystagmus.

Failure to follow ANY of these vital instructions could cause Nystagmus, which would other not be present, and will give a false result.   The officer’s goal is to find Nystagmus, which in his training tells him that the driver is intoxicated or impaired, which helps prosecute the case.  It’s quite rare that the dash cam video provides a full account of this test to ensure that the proper technique and instructions were provided  

When I look at the evidence in a DUI case, I carefully evaluate any information available to see if the HGN test was done properly.  If there is no video then I am going to cross-examine the officer on all of the instructions which are laid out in his training manual, and to make sure he followed it.  The officer may or may not have actually followed it, but usually if an officer is not telling the truth, something will pop up during a carefully tailored cross-examination.  
Usually the most fruitful result of this cross-examination is evidence that my client was facing headlights or traffic, which is now allowed per the training manual for a proper HGN test.  Putting the HGN test in question may not be the smoking gun to a not guilty verdict, but it can be a further minor victory when it comes to the officer’s credibility and attention to detail, which puts other parts of the case into question.  ​

The majority of DUI cases in Michigan have multiple BAC readings.  The first reading typically comes at the scene of the crime in the form of preliminary breath test.  Officers offer this test in order to assist in justifying their arrest.  The defendant has the option to take the test, or decline; if you decline, it’s a 2 point civil infraction.  In the end, this 2 point infraction is usually dismissed anyway as part of an agreement that is worked out with the prosecutor.  

Police officers aren’t always clear about the consequences of not taking the test, and are ok with my client believing that a refusal of the PBT will lead to loss of license, and 6 points on their license, which is not true (these sanctions apply to the Datamaster).

I typically believe taking the test only hurts your case, because if you blow over the limit, and there is evidence of driving, the officer has a slam dunk case for a legal arrest.  Without the test, an officer has to rely on his subjective observations, and if you decline field sobriety tests, then the officer really has to stretch his rationale, and we stand a great chance to challenge the arrest.  

In Michigan a police officer may arrest a person based in whole or in part on PBT results.  Once used as part of the arrest, the test is typically no longer admissible with limited exceptions.  

So the first part of beating the PBT is to not take it at all.  I’ve filed a lot of motions to challenge an arrest, because the cop did not have a PBT result as part of his arrest; we were able to attack field sobriety tests and officer observations and beat the arrest.  

If a PBT is administered, the question becomes, do we want to try to use the results to help or case, or make sure to keep it out of the case.  Most would say, let’s keep it out, because it’s evidence against me.  Here is how I have used the PBT to help my clients win at trial.  

Let’s assume my client is charged with a High BAC/Super Drunk offense in Michigan.  We have a PBT result of say 0.13, we then have a Datamaster result of 0.18 an hour later.  How can that benefit my client? Well a High BAC prosecution requires that the prosecutor prove beyond a reasonable doubt that when my client was driving his/her car, their BAC was over 0.17.  Well alcohol levels go up and down after your last drink.  The question is, when the police stop you, are you rising or falling in your BAC level?

With these two readings, we have a clear rise in BAC level.  This would assist in an argument that my client’s BAC was rising, and likely was below 0.17, and closer to the 0.13 result at the scene.  This type of scenario has helped me resolve cases with very favorable plea deals, especially in certain counties than never bargain on Super Drunk cases.  

We also use these numbers at trial, but in order to introduce the PBT at trial, we need to fit it into one of the three exceptions to the rule.  The three exceptions in Michigan are the following:

1. The test results may be admitted to assist the court or hearing officer in determining a challenge to the validity of an arrest. MCL 257.625a(2)(b)(i).
2. At trial, the defendant may offer the PBT result as evidence of his or her BrAC to rebut testimony elicited on cross-examination of a defense witness that the defendant’s BrAC was higher at the time of the charged offense than when a chemical test was administered. MCL 257.625a(2)(b)(ii).
3. At trial, the prosecution may introduce PBT results as evidence of the defendant’s BrAC only to rebut testimony elicited on cross-examination of a prosecution witness that is offered or elicited to prove that the defendant’s BrAC was lower at the time of the charged offense than when the chemical test was later administered (the rising blood or breath alcohol content defense). MCL 257.625a(2)(b)(iii).

In order to get the PBT into our case,  I would go for the second exception.  While it would not be automatically admitted, a crafty cross-examination of the DataMaster operator is likely to be fruitful.  

With the right judge, it is also possible to sneak the result in through the prosecution’s witness, and most judges in my experience would view the matter as a matter of fairness; if there’s another BAC reading out there that might assist the trier of fact (the jury), they may let it in, and let the jury decide what to do with it.  

The PBT is not automatically admissible because it is simply not as reliable as the Datamaster, which is tested, calibrated and checked on a regular basis (weekly and every 120 days).  Many PBT devices go long periods of time without calibrating and could sit in cold or hot weather for long periods of time.  The key is identifying the result, and how to use it to your advantage. ​