Many Texas DWI arrests begin with a roadside sequence familiar from television:
- follow the officer's finger
- walk heel-to-toe
- stand on one leg
Then the officer writes that the driver displayed a certain number of "clues" and concludes that the person was intoxicated.
Field sobriety tests can be important evidence.
They are not magic.
At Taylor Defense Firm, we examine what test was given, whether the officer used a standardized procedure, what instructions were actually provided, how the driver performed, what physical or environmental conditions existed, and whether the video supports the written report.
What Are Standardized Field Sobriety Tests?
The three tests most commonly associated with standardized roadside DWI investigation are:
- Horizontal Gaze Nystagmus
- Walk-and-Turn
- One-Leg Stand
These tests are designed to give officers observable information relevant to impairment.
But the reliability of the observations depends in part upon how the tests were administered and interpreted.
HGN Is Different From the Other Two Tests
Horizontal Gaze Nystagmus—often called HGN—does not require the driver to walk or balance.
The officer typically asks the person to follow a stimulus with the eyes while the officer observes eye movement.
The officer may look for standardized indicators associated with nystagmus.
Because the officer's observations are not always obvious on body-camera video, HGN can create different evidentiary issues from the Walk-and-Turn or One-Leg Stand.
We may examine:
- Was the stimulus positioned appropriately?
- Was the test performed long enough?
- Was the officer moving too quickly?
- Was the driver's head moving?
- Were lights or traffic distracting?
- Did the officer check for conditions that could affect the observation?
- Does the officer's training support the conclusions reported?
Walk-and-Turn Is a Divided-Attention Test
During the Walk-and-Turn, a person is typically asked to stand in a particular position, listen to instructions, walk heel-to-toe along a line, turn as instructed, and return.
The officer may report standardized observations concerning performance.
But the conditions matter.
We may examine:
- whether there was an actual line;
- the surface;
- slope;
- lighting;
- traffic;
- weather;
- footwear;
- injuries;
- age;
- balance problems;
- whether the person understood the instructions; and
- whether the officer demonstrated the test correctly.
The video often becomes more informative than the officer's shorthand notation.
One-Leg Stand Also Depends on Conditions
The One-Leg Stand typically requires the person to raise one foot, keep it elevated, and count while the officer observes performance.
Again, the test does not occur in a laboratory.
It may occur:
- on a shoulder;
- beside moving traffic;
- on uneven pavement;
- at night;
- in wind;
- after a collision;
- while the person is injured;
- while wearing difficult footwear; or
- under significant stress.
Those conditions do not automatically invalidate the test.
They do belong in the analysis.
"Clues" Should Be Connected to What Actually Happened
Police reports sometimes reduce performance to a number:
"Six out of eight clues."
"Four clues observed."
That number can sound scientific.
We want to know what conduct produced it.
Did the driver:
- step off the line?
- raise arms for balance?
- start too early?
- miss heel-to-toe?
- put the foot down?
- sway?
- misunderstand the turn?
The underlying performance should be compared with the officer's scoring.
Body-Camera Video Can Be Crucial
Field sobriety testing is one of the best examples of why video matters.
The officer may later describe the performance as poor.
The video may support that conclusion.
Or it may show a person who performs much better than the report suggests.
We may compare:
instructions → demonstration → actual performance → officer comments → written report.
Video may also reveal whether the officer repeatedly corrected the person, interrupted the test, changed instructions, or scored conduct not obvious from the recording.
The Tests Do Not Occur in a Vacuum
A person's physical condition can matter.
Relevant factors may include:
- back problems;
- knee injuries;
- ankle injuries;
- neurological conditions;
- inner-ear problems;
- age;
- weight;
- fatigue;
- recent surgery;
- head injury;
- medications; and
- disabilities.
These do not automatically explain poor performance.
But they can provide legitimate alternative explanations that should be considered.
Crash Cases Can Be Especially Problematic
A person who has just been involved in a collision may be:
- shaken;
- injured;
- sore;
- disoriented;
- frightened;
- exposed to flashing emergency lights;
- standing on debris;
- or dealing with emergency personnel.
Performance under those circumstances may not mean the same thing as performance by an uninjured person during a routine roadside stop.
The officer's decision to administer testing should be examined in the context of the crash scene.
Nervousness Can Affect Performance
Being stopped by police can be stressful.
A person may shake, talk quickly, forget an instruction, or struggle to concentrate.
Nervousness does not automatically explain every poor result.
It also should not automatically be treated as proof of intoxication.
The totality of the encounter matters.
Language and Understanding Can Matter
Field sobriety tests require understanding and following multi-step instructions.
If the person has difficulty understanding English, has hearing impairment, or does not understand what the officer is asking, performance may be affected.
We may examine:
- Was an interpreter used?
- Did the officer confirm understanding?
- Did the person ask for clarification?
- Was the officer speaking quickly?
- Were the instructions different from the standard procedure?
Misunderstanding should not automatically be scored as impairment without careful examination.
Footwear Can Matter
High heels, boots, sandals, loose footwear, or other shoes may make roadside balance testing more difficult.
The officer may allow removal of shoes in some situations.
Video can show whether footwear was a genuine issue and whether accommodations were offered.
The point is not that footwear defeats the test.
It is that physical conditions affecting performance should be evaluated rather than ignored.
Roadside Conditions Can Matter
The Walk-and-Turn and One-Leg Stand may be performed beside:
- traffic;
- gravel;
- uneven pavement;
- drainage slopes;
- curbs;
- construction;
- rain;
- wind;
- poor lighting; or
- flashing patrol lights.
A standardized test is still being administered in a real-world environment.
That environment should be visible in the defense analysis.
Officers Must Be Trained to Administer the Tests
Field sobriety evidence depends heavily upon the officer's observations.
We may therefore examine:
- training;
- certification where relevant;
- experience;
- refresher training;
- testimony concerning standardized procedures;
- the officer's report; and
- the video of actual administration.
The issue is not whether the officer has handled many DWI cases.
It is whether the particular tests in this case were administered and interpreted reliably.
Standardization Matters
Standardized testing derives much of its value from using a recognized procedure.
When the test is materially changed, the evidentiary significance of the result may require closer examination.
That does not mean every minor deviation automatically destroys the evidence.
It means the procedure should be compared with the method the officer claims to have followed.
Refusing Field Sobriety Tests Is Different From Refusing Breath or Blood
A request to perform roadside exercises is not the same thing as a later request for a breath or blood specimen.
Different legal rules and consequences may apply.
A person may perform some roadside tests and decline others.
Or the person may decline roadside exercises and later agree to a chemical specimen.
The sequence should be preserved accurately.
Field Sobriety Tests Do Not Measure Alcohol Concentration
A roadside balance test does not tell the jury:
"This person's BAC was .12."
Field sobriety evidence generally concerns observed performance and impairment.
Breath or blood analysis addresses chemical concentration.
Those are different forms of evidence.
A prosecution may contain one, both, or neither.
Good Performance Can Matter Too
Defense analysis should not focus only on mistakes.
We also examine what the driver did correctly.
Did the person:
- understand instructions;
- maintain balance;
- communicate clearly;
- follow the stimulus;
- walk appropriately;
- count correctly;
- remain cooperative; and
- display ordinary coordination?
Officers may emphasize standardized clues, but the jury may see the entire performance.
Poor Performance Does Not Automatically Prove Intoxication
A person can perform poorly for reasons unrelated to alcohol or drugs.
Likewise, a person who performs reasonably well may still be intoxicated under Texas law.
Field sobriety testing is therefore one part of the evidentiary picture.
Other evidence may include:
- driving;
- statements;
- odor;
- speech;
- blood or breath testing;
- witnesses;
- drug evidence;
- medical evidence; and
- video.
The State must prove intoxication beyond a reasonable doubt based upon the admissible evidence as a whole.
What Punishment Is at Stake?
Field sobriety testing is evidence, not a separate criminal offense.
The punishment depends upon the underlying DWI charge.
A basic first DWI under Texas Penal Code §49.04 is generally a Class B misdemeanor, carrying:
- 72 hours to 180 days in county jail; and
- a possible fine of up to $2,000.
If the State proves an alcohol concentration of 0.15 or more at the time the analysis was performed, the offense may be elevated to a Class A misdemeanor, generally carrying up to:
- one year in county jail; and
- a possible $4,000 fine.
Qualifying prior intoxication convictions can also increase the offense level and punishment, including felony exposure in appropriate repeat-offender cases.
Field sobriety performance does not determine the punishment range by itself.
But it may become a major part of the State's attempt to prove intoxication.
Build the Test From Instruction to Conclusion
At Taylor Defense Firm, we may reconstruct field sobriety evidence as:
officer observations → decision to test → instructions → demonstration → environmental conditions → physical condition of driver → performance → officer scoring → arrest decision → report → trial testimony.
We then ask:
- Was the officer trained?
- Was the test administered in a standardized manner?
- Were the instructions clear?
- Did the person understand them?
- Were physical or environmental limitations present?
- What does the video actually show?
- Does the officer's scoring match the recorded performance?
- What did the driver do correctly?
- What other evidence of intoxication exists?
- And does the complete evidence establish intoxication beyond a reasonable doubt?
Field sobriety tests can provide meaningful evidence in a Texas DWI prosecution.
But a roadside score should never substitute for watching the actual performance, examining the conditions, and determining whether the officer's conclusion is supported by what really happened.