Field Sobriety Testing and Chemical Testing

Standardized Field Sobriety Testing

Standardized Field Sobriety Tests were developed by the National Highway Traffic Safety Administration (“NHTSA”) in the mid seventies to establish a reliable and consistent methodology for evaluating intoxication.

NHTSA determined that three tests, if administerd in accordance with NHTSA guidelines, could accurately predict whether a person is under the influence such that the person cannot safely drive.  The three field sobriety tests approved by NHTSA are the Horizontal Gaze Nystagmus “HGN” test, the Walk-and-Turn test, and the One-Leg Stand test. No other tests have been approved by NHTSA, although the courts routinely approve admission of evidence of other types of tests.

1. Horizontal Gaze Nystagmus (“HGN”) Test

The Horizontal gaze nystagmus is a test designed to measure whether the eyes follow a moving object in a smooth steady fashion (indicative of sobriety) or in a jerking, irregular fashion (indicating intoxication). The HGN is highly unreliable and therefore is not admissible at trial in Pennsylvania. It can only be used to establish probable cause for requesting further testing with more reliable tests. NHTSA testing under strictly controlled conditions determined that the HGN only yields the correct result approximately 77% of the time, with the remainder yielding false results. It has also been proven that certain medications can mimic the signs of intoxication that show during the HGN testing.

2. Walk-and-Turn Test

The NHTSA instructions for the walk-and-turn test require the driver to take nine steps in a heel-to-toe fashion along a straight line. The driver must then turn on one foot and return in the same manner in the opposite direction.  The officer watches not only for problems with balance, but also for close adherence to the instructions provided. Thus, many people who have been tested and did not stumble or raise their arms are failed on the test even though they honestly believe that they passed. Most officers do not advise the driver of the results after each test. NHTSA studies have revealed that this test is only accurate about 68 percent of the time. Please be certain to let us know if you have an injury or physical condition that would hinder your ability to take the test or whether you were administered the test on loose gravel, near traffic, on an uneven surface, or without the benefit of a painted line. I actually once had a case wherein a driver was given field sobriety testing in an active lane of traffic on the Schuylkill Expressway with traffic flying past within mere feet of the testing.

3. One-Leg Stand Test

The one leg stand requires a driver to stand with one foot approximately six inches off the ground and count one thousand-one, one thousand-two, etc. until told to put the foot down after 30 seconds.  This test is only accurate 65 percent of the time.  Any physical limitations or injuries that could affect this test should be discussed with us.

It is important to carefully examine field sobriety test evidence.  In many – if not most – instances, police officers do not administer the test in full compliance with NHTSA guidelines.  For example, an officer’s opinion should be considered suspect if he uses improper scoring criteria, was improperly trained, incorrectly instructed the suspect on how to perform the test or did not use the standardized methodology in performing the tests.  Cross-examining police officers with their own training manuals frequently exposes their lack of knowledge and skill in conducting these tests.  At trial, all of these factors must be fully explored so that a judge and/or jury understand the weaknesses of field sobriety testing.

PBT or Preliminary Breath Testing with an Alco-Sensor device

Police in Pennsylvania may use a handheld PBT device for the sole purpose of determining whether there is sufficient cause to request a more reliable chemical test.  Although this test can be sufficient by itself, there is a Pennsylvania Supreme Court case “Brigidi” decided in October 2010 which requires that all such devices be properly calibrated, something police officers rarely do. In Montgomery County, Bucks County, and the surrounding Philadelphia communities the PBT is normally only used to obtain probable cause to request more reliable testing such as a blood test or a breath test back at the police station.

Blood Alcohol Testing

Pennsylvania state law prohibits police from performing a chemical test of a driver’s blood alcohol content (i.e., a breath test or a blood test) unless there are “reasonable grounds” to believe that the driver was operating a vehicle under the influence.  The police use field sobriety tests to help develop these “reasonable grounds” to submit motorists to chemical testing.

Anyone who drives in Pennsylvania is deemed to have given their consent to providing a breath, blood or urine sample when requested to do so by the police if (and only if) the police have reasonable grounds and have arrested the person for DUI.  Motorists who refuse chemical testing (assuming reasonable grounds to arrest exist) will have their license suspended for at least one year by PennDOT, and the fact that they “refused” the test may be used them at trial.

Whether a person is seeking admission into the Accelerated Rehabilitative Disposition (ARD) program or headed toward trial, it is important to carefully examine whether the police appropriately developed “reasonable grounds” to believe a driver may have committed a DUI.  Where “reasonable grounds” are found not to exist, all subsequent chemical testing may be suppressed.

The two most common chemical blood tests are blood testing and breath testing.

1. Blood Testing

Pennsylvania law requires health care workers to withdraw blood samples from DUI suspects unless there are intervening emergency situations at the hospital at the time the request is made.  Pennsylvania law also requires that blood (and urine) tests be performed at licensed and approved clinical laboratories using approved testing methods and equipment.

It is important to carefully examine blood test results to determine if the variance or margin of error may include the possibility that the true blood-alcohol content was in a lower tier or below 0.08 percent altogether.  If a person’s BAC test result is exactly .10 percent, no toxicologist can determine that the person’s actual blood alcohol concentration was above or below this level.  Instead, there is a margin of error of 3 to 10 percent within which the actual blood alcohol content would likely fall, and the driver can usually get the benefit of this doubt.

The Department of Health requires laboratories conducting blood-alcohol testing to test within 9 percent of a “known sample” in order to maintain their accreditation.  Accordingly, many toxicologists contend that the margin of error of blood testing at such accredited labs should be presumed to be no less that 9 percent.

Even if someone elects to seek admission into the Accelerated Rehabilitative Disposition (ARD) program or plead guilty to DUI it is important to evaluate whether the documented blood-alcohol content can be reduced using a margin-of-error analysis.  Anyone charged with DUI should carefully review all of these issues with an experienced criminal defense attorney.

2. Breath Testing

Police frequently test blood-alcohol content by using a “breathalyzer” machine.  These machines are much more accurate than the “PBT” units police use to test blood-alcohol content at the scene.  To be admissible at trial, breath tests must be conducted in conformity with regulations set forth by PennDOT.  These regulations require the machine to be regularly calibrated, the person operating the test to be certified, a 20-minute observation period prior to the testing, and two breath samples taken within a prescribed period of time.  The two breath test results must be within 0.02 percent of each other.  Failure to comply with any of these regulations can result in the results being suppressed (inadmissible) at trial.

As with blood testing, breath test results have a margin of error that should be considered in determining a person’s actual blood-alcohol content. Another excellent defense to breath testing exists for persons suffering from GERD or acid reflux. Persons charged with DUI must discuss these important issues with their attorney.