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DUI Field Sobriety Tests in Pennsylvania

Lehigh Valley DUI Attorneys in Easton, Pennsylvania

Pennsylvania DUI Field Sobriety Tests

Field Sobriety Tests Conducted in Pennsylvania DUI Stop

When Pennsylvania Police conduct a DUI stop, they follow, predetermined, standardized DUI policy and procedures.  The Lehigh & Northampton County DUI stop typically begin with either a moving violation or an equipment violation.  If the basis of the stop is a moving violation, that violation may be evidence of DUI.  However, if the stop is for an equipment or licensing violation, with no moving violation, that may lead to evidence against a finding of DUI.

Once a stop has been conducted. the police officer will approach the vehicle and ask the driver if he or she knows why they were pulled over, this allows the officer to check for speech patterns and cognitive ability.  The officer then asks the driver for his documentation, license and registration.  The officer uses this time to check the driver’s recollection and basic motor skills.

The officer may state that he smells drugs or alcohol and, if so, will ask the driver how much he or she has had to drink.  This is done to obtain any possible admissions to DUI from the driver.  

Finally, the police officer will ask the driver to exit the vehicle and ask him or her to perform three (3) standardized DUI field sobriety tests (FSTs).  The officer may or may not administer a portable breathalyzer test, a PBT, at this point.

Below we will discuss the various field sobriety tests and their purposes and pitfalls as it pertains to DUI Defense in the Lehigh Valley.

Checkpoint for DUI in Easton

DUI Field Sobriety Tests

Accuracy Under Perfect Conditions & Administration
Horizontal Gaze Nystagmus (HGN)77%

Destined to Fail

Justification rather than investigation

Field Sobriety Tests, FSTs for short, include three (3) primary tests: Horizontal Gaze Nastagmus (HGN), One-Leg-Stand & Walk-and-Turn.

All FSTs suffer from a number of problems undermining their accuracy.  The very first which is a lack of regular training provided Easton, Allentown & Bethlehem police officers in administering DUI tests.  Additionally, many police safety procedures are directly at odds with the DUI tests.  For example, police are trained to always keep themselves between a suspect and their police vehicle.  This same policy requires that the driver face the police vehicle, with its flashing lights, while taking the FSTs.  However, FST instructions warn against facing the driver in the direction of any bright lights.  Finally, the FSTs were developed in a controlled setting without the stresses of a traffic stop or uncontrolled physical factors such as weather, incline, level, shoe fit, physical fitness and many more.

For an synopsis of each individual Field Sobriety Test administered by Police in a Pennsylvania DUI stop, read below.

Horizontal Gaze Nystagmus - HGN

Ophthalmologist or Police Officer?
Accurate Under Perfect Conditions
Accurate As Performed

The HGN test is not admissible in court in Pennsylvania.  Nonetheless, police in Allentown, Easton & Bethlehem continue to use this supposed test during DUI investigations.

Nystagmus is an involuntary “jerking” or darting of the eyes.  Nystagmus can be brought on by alcohol but can also be caused by a number of other things, including nicotine, caffeine and lack of sleep.  For the HGN test to have any value, both the police officer and the tested individual must be qualified for the test.  Unless the officer has a medical degree, the officer is not qualified to give the HGN test.  The person administering the test must also qualify the person being tested.  To qualify the person being tested, the person conducting the test must ascertain from the subject’s medical history and present condition, whether they are suitable for testing.  As the vast majority of police are not qualified to give the test, they are unqualified to qualify the test subject. 

The HGN test has been found to be 77% accurate if performed by a qualified medical professional.  As it is the most accurate FST, if performed correctly, this explains why it is still regularly used despite being inadmissible in court.

For a much more in depth overview of the HGN test look at our sample HGN cross examination from a real Pennsylvania DUI case.

Walk-And-Turn Test - DUI Field Sobriety Test

9-steps forwards, 9 steps back, heel-to-toe but only when told
Accurate Under Perfect Conditions
Accurate As Performed

During the walk and turn test the police officer is required to read a series of instructions to a DUI suspect.  The police officer then asks the driver to take 9 heel-to-toe steps in one direction, turn and take 9 more heel-to-toe steps back to the starting position.  The officer then looks for 8 clues, or indicators of intoxication during a Pennsylvania DUI stop:

  1. Can the alleged DUI driver keep his or her balance during instructions?
  2. Does the alleged DUI driver start too soon? 
  3. Does the alleged DUI driver pause during the test?
  4. Does the alleged DUI driver touch heel-to-toe
  5. Does the alleged DUI driver step of the alleged (read imaginary) line?
  6. Does the alleged DUI driver use his or her arms to balance
  7. Does the alleged DUI driver turn properly?
  8. Does the alleged DUI driver take the right number of steps?

Numerous problems in the everyday application of the Walk-And-Turn DUI test.  The test must be conducted on level, hard, dry ground but this is infrequently adhered to.  The DUI suspect must be wearing comfortable footwear, not heels, loose boots or slippers.  The DUI suspect must also be under 60 years of age and moderately physically, and mentally, fit for the test to have any value. 

The walk-and-turn test has been found to be 68% accurate by government studies but only if administered in perfect conditions, by a highly trained administrator.

For a more detailed explanation of the problems with the walk-and-turn test, see our sample walk-and-turn cross-examination from an actual DUI case conducted by our Lehigh Valley DUI Lawyers.

One-Leg-Stand - DUI Field Sobriety Test

Balancing Act
Accurate Under Perfect Conditions
Accurate As Performed

When conducting the one-leg stand test during a Lehigh Valley DUI stop, Pennsylvania police instruct the DUI suspect to stand with one foot, six inches off the ground, and count aloud until told to stop.  (which should happen in 30 seconds).  The One-Leg-Stand-Test has four clues, or indicia of intoxication:

  1. Does the DUI suspect sway while balancing?
  2. Does the DUI suspect use his arms for balance?
  3. Does the DUI suspect hop on one foot? 
  4. Does the DUI suspect put the foot down early?

Problems with the one-leg-stand test include: unsuitable surface conditions, a lack of physical or mental fitness in the DUI suspect, improper footwear, improper timing by the police officer and any movement by the police officer can cause imbalance in the tested individual.

The one-leg-stand test is 65% accurate but only when administered correctly and under perfect conditions, according to government studies.

Read our actual cross-examination on the one-leg-stand test from an actual Lehigh Valley DUI case for more information.

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Lehigh & Northampton County DUI Defense Staff