Illinois DUI Evidence

Upon an arrest for DUI in Illinois, you will be taken to the police station and asked to submit to a chemical test of your blood, breath, or urine for purposes of detecting drugs or alcohol present in your system. Breath tests are used only to determine your blood alcohol content (BAC). Blood and Urine testing can measure amounts of alcohol as well as drugs that are present in your system. Which test(s) will be requested depend on the circumstances of your particular case, and the law enforcement agency that has made your arrest. The police have the discretion as to how many and which particular tests they will request. Illinois law allows the police to request a urine sample after a blood or breath sample has been obtained (usually in cases where drug impairment is suspected). Generally, if you refuse to submit to a chemical test, then no test will be given, but penalties for your refusal will apply (see the Illinois Driving tab for more information). Additionally, your refusal will be admissible against you in court as evidence of your guilt. For DUI suspects who are unconscious, a blood testing will be conducted regardless of the suspect's consent (the law assumes consent was given).

The types of DUI evidence in Illinois drunk driving cases

RIGHT TO ADDITIONAL TEST - Illinois law provides DUI suspects with the right to have independent chemical testing conducted in addition to the chemical test(s) that are administered by the police. The independent test must be paid for by the DUI suspect, and it must be conducted by a qualified person in accordance with the statutory rules or the results will not be admissible in court. Failure to obtain independent testing will not affect the admissibility of the test(s) administered by the police.

BREATH TESTING - Breath testing in Illinois may be conducted on scene with a handheld breath testing device, or at the station with an evidentiary breath test machine. Portable Breath Tests (PBTs) are typically used only on scene to help the officer determine whether he has probable cause to make an arrest. The results are generally inadmissible in court and there is no penalty for refusing. Evidentiary breath tests are considered more reliable and are generally admissible in court. Prior to administering an evidentiary breath test, the police are required to observe a DUI suspect for 20 minutes to ensure that nothing foreign is placed into their mouth that could produce invalid results. In general, breath testing is not the most reliable method for determining a person's BAC, but it is the most commonly administered chemical test because it is convenient. A suspect will breath into the test unit through a tube that is connected to the breath machine. The machine will measure the amount of alcohol present on the suspect's breath and provide an immediate printout result. All breath testing must be conducted on approved machines using methods and procedures in accordance will the rules and regulations that govern chemical test administration. Only qualified persons may administer a breath test.

BLOOD TESTING - Illinois law requires blood testing to be performed by a licensed physician, nurse, or other qualified person. Blood test analysis must be conducted in accordance with the rules and procedures that govern chemical testing in Illinois DUI cases. Failure to properly preserve or label the sample and problems with the chain of custody are common defenses to the admissibility of blood test results. Blood testing is the most invasive method of determining BAC, but it is also the most reliable. For DUI cases involving drugs, blood testing is the chemical test of choice, as breath machines are incapable of measuring drug levels and urine analysis cannot always detect the existence of specific drug metabolites.

URINE TESTING - Urine testing is available as an alternative to breath and blood testing in Illinois DUI cases. Although the laws state that the police are allowed to request a urine test after a breath or blood test has been performed, urine testing is no longer used in Illinois DUI cases as the results are rarely admissible in court.