Walking the Imaginary Line

Prosecutor Western Justice has an amusing – so amusing it’s possibly fake? – video up on his website from a DWI arrest. Basically, it’s the falling over type.

WJ introduces the video with this thought:

Defense attorneys always make a big deal that the walk and turn test is on an imaginary line! (gasp). Well, even though it really does not matter if it is an imaginary line or an actual line, here is another reason why some police officers use an imaginary line.

Well, yes, defense attorneys do ‘make a big deal’ about that, and let’s talk about why.

Police officers come into court and testify that attending a Field Sobriety Testing course taught by another police officer makes them an expert in DWI, and juries generally believe them.

In return, DWI lawyers ask jurors to believe the manual from the training the officer received. Seems like a fair bargain.

One common misconception that I see over and over on the part of officers, up to and including some of the local Austin DWI task force officers, is the belief that book doesn’t require that a designated actual line be used.

If asked why the defendant was asked to walk an imaginary line instead of an actual line, most officers reply – some smugly – that ‘the manual’, that is the NHTSA manual, doesn’t require it. Some offer to show the defense lawyer exactly where in the book it says they don’t have to use an actual line.

Invariably, the officer will flip the pages and find this portion of the manual:

Procedures for Walk and Turn Testing

1. Instructions Stage: Initial Positioning and Verbal Instructions

For standardization in the performance of this test, have the suspect assume the heel-to-toe stance by giving the following verbal instructions, accompanied by demonstrations:

“Place your left foot on the line” (real or imaginary). Demonstrate.

[I’m taking this from the February 2006 Edition, Student Manual, page VIII-9 from Session VIII: Concepts and Principles of the Standardized Field Sobriety Tests. It should be in Chapter 8 of most or all other manuals.]

That certainly looks at first blush as if the manual says there’s no difference between the difficulty between walking an actual line, or walking an imaginary line. Although, it literally begs the question, “Officer, how wide a line did my client imagine?”

But no. The officer who so testifies is wrong. (Sorry, WJ, you’re wrong too.)

Flip the page once more – VIII-11 in the one I’m reading now - and you come to the part entitled:

4. Test Conditions

Walk-and-Turn test [sic] requires a designated straight line, and should be conducted on a reasonable dry, hard, level, nonslippery surface.

Requires. So, how to explain the seeming discrepancy? Easy.

The first section is talking about “Verbal Instructions” and is clearly labeled so. It is the Instructions Stage. That means… it is talking about the portion of the test where the officer demonstrates the Walk and Turn to the suspect.

So, going by the book, it’s perfectly OK for the officer to show the defendant how to do the test on his own imaginary line if he wants to do it that way. Heck, we all know they don’t even have to demonstrate all 9 steps. They are allowed to do it that way.

But the NHTSA Manual makes no bones about it: if this test is going to be administered properly, then the defendant is supposed to be afforded the opportunity to do it on an actual line. It is literally: required. And yes, that’s a potentially reasonable explanation for someone stepping ‘off the line’ – it wasn’t there in the first place.

Perhaps WJ’s point was that sometimes the defendant is so obviously impaired that it wouldn’t make any difference whether there was an actual line or not. And yes, I have represented more of my fair share of those types of cases.

But as for defense lawyers insisting that their DWI clients be graded properly… I don’t see anything wrong with that.

Visual Detection of DWI Motorcyclists: NHTSA Manual

The primary student manual “DWI Detection and Standardized Field Sobriety Testing” published in February 2006 by NHTSA spends less than half a page on its subsection “Visual Detection of DWI Motorcyclists”. It’s in Chapter 5, Phase One “Vehicle in Motion” immediately after the section on visual cue descriptions for auto motorists.

However, in March of 2005 NHTSA published a brochure on the subject entitled “The Detection of DWI Motorcyclists”.

From both sources, the list of driving cues that officers are trained to look for in Motorcycle DWI/DUI cases are listed as either excellent (above 50% chance) or good (30-50% chance):

Excellent Cues

  • Drifting during turn or curve
  • Trouble with dismount
  • Trouble with balance at stop
  • Turning problems
  • Inattentive to surroundings
  • Inappropriate or unusual behavior
  • Weaving

Good Cues

  • Erratic movements while going straight
  • Operating without lights at night
  • Recklessness
  • Following too closely
  • Running stop light or sign
  • Evasion
  • Wrong way

Good fodder for DWI lawyers in motorcycle cases where the defendant is stopped ‘only’ for speeding (which is pretty common)…page 5 of the brochure:

Motorcyclists stopped for excessive speed are likely to be driving while intoxicated only about 10 percent of the time (i.e., 10 times out of 100 stops for speeding). But because motorcyclists tend to travel in excess of posted speed limits, speeding is associated with a large portion of all motorcycle DWI arrests.

In other words, while only a small proportion of speeding motorcyclists are likely to be considered DWI, the large number of motorcyclists who are speeding results in a large number of DWIs, despite the relatively small probability.

In cross examination, this can be used if the stopping officer testifies that speeding is a sign of intoxication (which belies the common sense of the jury as well).

Also, the officer should be crossed on all the things your client did right: no drifting, no trouble dismounting, etc.

DWI lawyers should consider asking the officer whether the dismount itself is a useful sobriety test. Many officers will openly scoff at the notion…that’s fine. Prod him to insist that only the NHTSA field sobriety tests are appropriate for evaluating the likeliness of intoxication or impairment.

Then have him read this paragraph from pp7-8 from the NHTSA brochure:

Trouble with Dismount

Parking and dismounting a motorcycle can be a useful field sobriety test. The motorcyclist must turn off the engine and locate and deploy the kickstand. The operator must then balance his or her weight on one foot while swinging the other foot to dismount. But first, the operator must decide upon a safe place to stop the bike. Problems with any step in this sequence can be evidence of alcohol impairment.

And having absolutely no trouble with the dismount is at least some evidence of a lack of impairment, correct Officer? (Doesn’t matter how he answers; the jury gets the point.)

NHTSA Field Sobriety Test "Accuracy" Rates; What Do They Really Mean?

Dr. Greg Kane at Med-Mal Experts has published an excellent 3 part series on the flawed math that NHTSA uses to calculate “accuracy rates” for the Field Sobriety Tests. These papers were originally published in the Colorado Trial Lawyer’s Association magazine Trial Talk, and are now reproduced on Kane’s website “The predictive value of the NHTSA’s Standardized Field Sobriety Tests”.

Ultimately, Kane answers the question that all DWI lawyers need to be asking: What does it really mean when the officer testifies that “failure” of the field sobriety tests means there is a 93% chance that the defendant was intoxicated? How did NHTSA come up with that number…and is it meaningful?

From Kane’s site:

Around the country, DUI defense attorneys form organizations, give seminars and share trial strategies to overcome FST evidence. Prosecutors do the same, from the other direction. The two sides bicker about mechanics. Did the officer follow procedure exactly? Did the officer consider medical conditions that cause incoordination?

What no one does, as far as I can tell, is doubt the NHTSA "validation" contractors' analysis of what a mechanically meticulous coordination test actually implies about alcohol impairment. The driver failed the FST. No one asks, "Exactly what does that mean?"

I have to admit that he’s right. DWI defense lawyers and prosecutors tend to argue back in forth about whether the officer administered the tests properly. And any good DWI lawyer better know the NHTSA manual back and forth, so that when he watches the videotape of his client on the scene, he can evaluate the officer’s performance as well as his client’s.

But is it possible that we in the DWI defense bar have been missing the forest for the trees? I’ve digested the first paper thoroughly, and frankly, am truly excited about Kane’s work in these areas. As soon as I make it through the next two, I’ll post more on this subject.

Do Field Sobriety Tests Measure Impairment?

Every good DWI lawyer is familiar with the last section in Chapter 8 of the NHTSA DWI Detection and Standardized Field Sobriety Testing Manual that states:

If any one of the standardized Field Sobriety Test elements is changed, the validity is comprised. (***)

Indeed, one of the bedrocks of DWI defense is being able to grade not only the defendant’s performance on the FSTs, but being able to grade the officer’s administration of the tests. In some situations, improper instructions or grading can actually make an individual test or even the entire battery of tests inadmissible.

Unfortunately, for all NHTSA’s efforts to the contrary, there are many problems with these roadside tests – even when administered by the book.   They do not, in fact, allow police officers to accurately determine whether someone is over a .08 blood or breath alcohol content.

Furthermore, most of the better trained officers will admit under cross examination that there is no correlation between some of the tests and “impairment” – I know most of the specialized Austin DWI task force officers will testify to that, because I’ve asked them under oath. 

To the extent that “science” is involved here at all, the only real measurement is between performance on the tests, and being above or below a certain BAC.  Which means there’s an inherent argument for defense lawyers in many DWI breath test refusal cases that the client’s performance on the field sobriety tests is not sufficient proof of intoxication.

(*** Every NHTSA Manual I’ve ever seen actually has this section in ALL CAPS AND BOLD – emphasizing that even NHTSA acknowledges how important this is.)

NHTSA DWI Detection Manual - Glossary of Terms and Definitions

Alveolar Breath – Breath from the deepest part of the lung.

Blood Alcohol Concentration (BAC) – the percentage of alcohol in a person’s blood.

Breath Alcohol Concentration (BrAC) – The percentage of alcohol in a person’s breath, taken from deep in the lungs.

Clue – Something that leads to the solution of a problem.

Cue – A reminder or prompting as a signal to do something. A suggestion or hint.

Divided Attention Test – A test which requires the subject to concentrate on both mental and physical tasks at the same time.

DWI/DUI – The acronym “DWI” means driving while impaired and is synonymous with the acronym “DUI”, driving under the influence or other acronyms used to denote impaired driving. These terms refer to any and all offenses involving the operation of vehicles by persons under the influence of alcohol and/or other drugs.

DWI Detection Process – The entire process of identifying and gathering evidence to determine whether or not a suspect should be arrested for a DWI violation. The DWI detection process has three phases:

    • Phase One – Vehicle in Motion
    • Phase Two – Personal Contact
    • Phase Three – Pre-arrest Screening

Evidence – Any means by which some alleged fact that has been submitted to investigation may either be established or disproved. Evidence of a DWI violation may be of various types:

    • a.  Physical (or real) evidence: something tangible, visible, or audible.
    • b.  Well established facts (judicial notice).
    • c.  Demonstrative evidence: demonstrations performed in the courtroom.
    • d.  Written testimony or documentation.
    • e.  Testimony.

Field Sobriety Test – Any one of several roadside tests that can be used to determine whether a suspect is impaired.

Horizontal Gaze Nystagmus (HGN) – An involuntary jerking of the eyes as they gaze toward the side.

Illegal Per Se – Unlawful in and of itself. Used to describe a law which makes it illegal to drive while having a statutorily prohibited Blood Alcohol Concentration.

Nystagmus – An involuntary jerking of the eyes.

One Leg Stand (OLS) – A divided attention field sobriety test.

Personal Contact – The second phase in the DWI detection process. In this phase the officer observes and interviews the driver face to face; determines whether to ask the driver to step from the vehicle; and observes the driver’s exit and walk from the vehicle.

Pre-arrest Screening – The third phase in the DWI detection process. In this phase the officer administers field sobriety tests to determine whether there is probable cause to arrest the driver for DWI, and administers or arranges for a preliminary breath test.

Preliminary Breath Test (PBT) – A pre-arrest breath test administered during investigation of a possible DWI violator to obtain an indication of the person’s blood alcohol concentration.

Psychophysical – “Mind/Body”. Used to describe field sobriety tests that measure a person’s ability to perform both mental and physical tasks.

Standardized Field Sobriety Test Battery – A battery of tests, Horizontal Gaze Nystagmus, Walk and Turn, and One-Leg Stand, administered and evaluated in a standardized manner to obtain validated indicators of impairment on NHTSA research.

Tidal Breath – Breath from the upper part of the lungs and mouth.

Vehicle in Motion – The first phase in the DWI detection process. In this phase the officer observes the vehicle in operation, determines whether to stop the vehicle, and observes the stopping sequence.

Vertical Gaze Nystagmus – An involuntary jerking of the eyes (up and down) which occurs when the eyes gaze upward at maximum elevation.

Walk and Turn (WAT) – A divided attention field sobriety test.

Types of Nystagmus: 2006 NHTSA Manual

In Chapter 8 of NHTSA’s “DWI Detection and Standardized Field Sobriety Testing” Manual is a subsection entitled “Overview of Nystagmus”:

Nystagmus is defined as an involuntary jerking of the eyes. Alcohol and certain other drugs cause Horizontal Gaze Nystagmus.

Categories of Nystagmus

There are three general categories of nystagmus:

1. Vestibular Nystagmus is caused by movement or action to the vestibular system.

2. Nystagmus can also result directly from neural activity.

3. Nystagmus may also be caused by certain pathological disorders

Vestibular Nystagmus: NHTSA Manual 2006

Vestibular Nystagmus is caused by movement or action to the vestibular system.

A. Types of vestibular nystagmus:

Rotational Nystagmus occurs when the person is spun around or rotated rapidly, causing the inner fluid in the ear to be disturbed. If it were possible to observe the eyes of a rotating person, they would be seen to jerk noticeably.

Post Rotational Nystagmus is closely related to rotational nystagmus: when the person stops spinning, the fluid in the inner ear remains disturbed for a period of time, and the eyes continue to jerk.

Caloric Nystagmus occurs when fluid motion in the canals of the vestibular system is stimulated by temperature as by putting warm water in one ear and cold in the other.

Positional Alcohol Nystagmus (PAN) occurs when a foreign fluid, such as alcohol, that alters the specific gravity of the blood is in unequal concentrations in the blood and the vestibular system.

Nystagmus Resulting from Neural Activity: NHTSA Manual 2006

Nystagmus can result directly from neural activity:

Optokinetic Nystagmus occurs when the eyes fixate on an object that suddenly moves out of sight, or when the eyes watch sharply contrasting moving images. 

Examples of optokinetic nystagmus include watching strobe lights, or rapidly moving traffic in close proximity. The Horizontal Gaze Nystagmus test will not be influenced by optokinetic nystagmus when administered properly.

Physiological Nystagmus is a natural nystagmus that keeps the sensory cells of the eyes from tiring. It is the most common type of nystagmus. It happens all the time, to all of us. This type of nystagmus produces extremely minor tremors or jerks of the eyes. These tremors are generally too small to be seen with the naked eye. Physiological nystagmus will have no impact on our (NHTSA) Standardized Field Sobriety Tests, because its tremors are generally invisible.

Gaze Nystagmus occurs as the eyes move from the center position. Gaze nystagmus is separated into three types:

(1) Horizontal Gaze Nystagmus occurs as the eyes move to the side. It is the observation of the eyes for Horizontal Gaze Nystagmus that provides the forst and most accurate test in the Standardized Field Sobriety Test battery. Although this type of nystagmus is most accurate for determining alcohol impairment, its presence may also indicate the use of other drugs.

(2) Vertical Gaze Nystagmus (VGN) is an involuntary jerking of the eyes (up and down) which occurs when the eyes gaze upward at maximum elevation. The presence of this type of nystagmus is associated with high doses of alcohol for that individual and certain other drugs. The drugs that cause Vertical Gaze Nystagmus are the same ones that cause horizontal Gaze Nystagmus.

Note: There is no drug that will cause Vertical Gaze Nystagmus that does not cause Horizontal Gaze Nystagmus. If Vertical Gaze Nystagmus is present and horizontal Gaze Nystagmus is not, it could be a medical condition.

(3) Resting Nystagmus is referred to as a jerking of the eyes as they look straight ahead. Its presence usually indicates a pathology or high doses of a Dissociative Anesthetic drug such as PCP. If detected, take precautions.  (Officer Safety)

Nystagmus Resulting from Pathological Disorders: NHTSA Manual 2006

Nystagmus can be caused by certain pathological disorders. They include brain tumors and other brain damage or some diseases of the inner ear. These pathological disorders occur in very few people and in even fewer drivers.