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DUI Testing: Field Sobriety Tests, Blood Tests, and Breathalyzers

When a law enforcement officer stops a vehicle for a traffic infraction, he or she may be looking for signs that the driver is under the influence of alcohol. If an officer becomes suspicious and thinks that the driver is a potential DUI suspect, he or she will likely ask the driver to submit to a field sobriety test. This is the first in a battery of possible tests used by law enforcement to determine whether to arrest and charge someone for driving under the influence. If you have been arrested and charged with DUI in the Chicago metropolitan area, you should immediately seek the assistance of a seasoned criminal defense law firm like the Law Offices of David L. Freidberg, P.C. to help you assert your rights at the outset of the case.

Voluntary Field Sobriety Tests and Preliminary Breath Screening Test

Initially, a Chicago law enforcement officer will likely ask a suspected DUI offender to do a field sobriety test. Under Section 11-501.2(a-5) of the Illinois Compiled Statutes, Chapter 625, Part 5 (625 ILCS 5/11-501.2), officers are permitted to use standardized field sobriety tests approved by the National Highway Traffic Safety Administration (NHTSA) when conducting an investigation of a potential DUI violation. This test is purely voluntary, and individuals may refuse to take it.

According to an article by the Illinois State Bar Association, field sobriety tests were developed by NHTSA in conjunction with the Southern California Research Institute, which found that three tests – the Horizontal Gaze Nystagmus (HGN) test, the walk and turn test, and the one-leg stand test – were the most accurate and effective method of detecting alcohol impairment. These three tests are administered according to NHTSA protocols. However, it also found that these tests were not conclusive, and should only be considered along with other evidence of intoxication.

  • The Horizontal Gaze Nystagmus (HGN) is the involuntary movement of the eyes when they gaze to the side. The NHTSA states that the eyes will begin to jerk to the side sooner as an individual’s blood alcohol concentration increases. NHTSA believes that the HGN test is 77 percent accurate.
  • The Walk and Turn test is what the NHTSA calls a divided attention test. This test shows whether a person’s capabilities consist of the same mental and physical abilities that a person needs to be able to drive safely. This test consists of an instruction stage and a walking stage, and officers can see if a person can’t balance during instructions, starts too soon, takes the wrong number of steps, loses balance on turn or turns incorrectly, etc. If a person exhibits two or more of the clues outlined by NHTSA, then that person’s blood alcohol content is likely to be above 0.10. NHTSA acknowledges that this test is shown to be accurate only 68 percent of the time.
  • Similar to the Walk and Turn test, the One-Leg Stand Test also consists of two stages – an instruction stage and a balance and counting stage. It reveals what NHTSA considers as clues of intoxication, such as swaying while balancing, using arms to balance, hopping, or putting a foot down. If two or more clues are detected, then that person’s blood alcohol content is likely .10. NHTSA believes this test is 65 percent accurate.

Illinois courts have long allowed that field sobriety test results may be considered as evidence supporting a DUI conviction only if the prosecution can prove that the officer who administered the test was trained in the procedure and that the test was properly administered. In fact, the Illinois Supreme Court stated that field sobriety tests are admissible when performed according to the established NHTSA protocols by a properly trained officer. Therefore, those charged with DUIs may be able to challenge the validity of a field sobriety test by showing that either the officer who conducted it was not properly trained or that the officer failed to administer it according to NHTSA procedures.

Additionally, Section 11-501.5 of the Illinois Compiled Statutes, Chapter 625, Part 5 (625 ILCS 5/11-501.5) allows law enforcement officers to request for persons suspected of DUI to provide a sample of his or her breath for a preliminary breath screening test using an approved portable device, which is usually called a breathalyzer. However, the statute also permits individuals to refuse the test, the results of which may be used by the officer to determine whether to require a chemical test.

Breathalyzer tests are meant to evaluate a person’s blood alcohol level. However, the reliability of breathalyzer test results is often challenged. When equipment is improperly maintained at appropriate intervals, it may show inflated alcohol levels that are not accurate. Additionally, user error may also result in flawed breathalyzer test results, as well as the use of over-the-counter hygienic products such as mouthwash.

Implied Consent for Chemical Tests (Blood, Breath, and Urine)

According to 11-501.1(a) of the Illinois Compiled Statutes, Chapter 625, Part 5 (625 ILCS 5/11-501.1(a)), any person who drives or is in physical control of a motor vehicle on state highways are deemed to have consented to a chemical test of blood, breath, or urine for the purpose of determining its alcohol content, if an officer with probable cause to believe that the person committed a DUI and arrests him or her. If a person refuses to submit to a chemical test, he or she faces a possible driver’s license suspension. For a first-time refusal, the Illinois State Department may impose a 1-year license suspension, and for a second refusal within five years of the first, a 3-year license suspension may be imposed.

The implied consent statute also requires that law enforcement officers should provide a clear warning to those requested to submit to chemical tests. The warning should inform persons that refusal to submit to the test, or if the test reveals a blood alcohol content greater than 0.08, will result in statutory summary suspension of their driver’s licenses. If an officer fails to provide this warning, a court will likely deem the results of the test inadmissible as evidence.

While chemical tests are often regarded as the most reliable form of DUI testing in Chicago and the surrounding suburbs, there are still potential issues that can affect the results of these tests. For example, similar to breathalyzers, outdated or poorly maintained equipment can result in inaccurate alcohol readings, as well as improper use by testers employed by police departments. Additionally, chemical tests are governed by administrative rules promulgated by the Illinois Department of State Police, and if the procedures provided by these rules are not properly followed, there may be issues in how samples are collected, stored, transferred, and tested that introduced inaccuracies in the results.

There are many complex legal issues involved in DUI, and challenging the tests administered by law enforcement officers are merely one part of a good defense. If you have been charged with a DUI in the Chicago metropolitan area, the Law Offices of David L. Freidberg, P.C. can help you craft the most effective defense against that charge. David Freidberg has years of experience in criminal defense, including defending DUI cases. An attorney’s involvement as early as possible in a case often leads to better outcomes, so please do not hesitate to contact us today at (312) 560-7100 or toll-free at (800) 803-1142 for a free initial consultation. You may also complete our online form or send us an email, and we will respond to you as soon as possible.