DUI Blood Tests in Illinois

Updated on 01/13/2023 / Under

Blood testing is one of several chemical tests allowed in Illinois to be used as evidence of a DUI. These tests are usually the most reliable and can be difficult to face in court, but there are several ways to successfully challenge them.  That is where an attorney can be invaluable to your case. Call our Naperville DUI lawyers today at (630) 425-0250 to schedule a case evaluation and review how we can challenge DUI blood tests in Illinois.

Why Administer a Blood Test?

A police officer may use one of several chemical tests when a driver is suspected of a DUI. The officer gets to decide which type of test to administer:  breath, blood, or urine.  Of these, breathalyzer tests are the most common due to their convenience and the speed with which they can be used. 

The downside of this is that breath testing is not the most reliable when testing for blood alcohol concentration, nor can breathalyzer machines detect drugs (legal or illegal) in the bloodstream.  Blood testing for a DUI may be chosen by an officer either for its greater reliability or to test for drugs rather than alcohol.  Blood tests are typically conducted at a hospital, though some police departments have clinical facilities within their stations they may use for drawing blood. 

Blood tests usually follow several steps to get from the initial blood sample to usable evidence in a case.  A nurse or phlebotomist will the blood into vials, which are then marked as evidence and stored before being transported to one of several laboratories in Illinois for testing. the tubes are then marked as evidence, stored, then transported to a crime laboratory in Illinois for testing.

Blood is tested at a lab using a process called gas chromatography and the results are analyzed and a report is sent back to the police department for use in your trial.  These procedures add a number of changes in custody for your blood sample and can often be an area an experienced defense attorney can challenge. 

Can I Refuse a Blood Test in Illinois?

The short answer for most cases: Yes, but you shouldn't.  This is because the consequences for refusing a chemical test are often harsher than those you may get if you fail and receive a sentence. An offender's driving privileges will face automatic suspension by the Illinois Secretary of State for refusing to submit to chemical testing through a statutory summary suspension. Suspension periods in these cases are:

  • 1 year if the motorist has no prior DUI conviction or statutory summary suspension within the last five years
  • 3 years if the motorist has a prior DUI conviction or a statutory summary suspension with the last five years.

Related: Refusing a Field Sobriety Test in Illinois

The officer will generally take possession of the offender's license at the time of the arrest and issue a 45-day driving permit, with the license suspension taking effect on the 46th day. 

Additionally, a motorist who refuses a chemical test at the request of law enforcement will not be eligible for a driving permit while the suspension is in effect, may be held liable for the costs of a blood test, and the evidence of refusal shall be used against them in their DUI case.

The officer may also administer a chemical test without the consent of the driver in certain situations. For example, if an officer has probable cause to suspect a vehicle driven by someone under the influence of alcohol or other drugs has been involved in the personal injury or death of another person, that driver must submit to a chemical test.

DUI Blood Tests in Illinois

How Reliable is Blood Testing?

Blood tests tend to be more reliable than either breath tests or urine tests when performed on people accused of a DUI.  They also allow for more informed testing than a breathalyzer, registering not only blood alcohol content but also the presence of a prescription or illegal drug in the bloodstream.  This increase in reliability does not, however, mean that the test results are infallible.  The entire process is still susceptible to human error in terms of adherence to protocol, proper handling of the sample, or even something as simple as confusing one sample for another.  

With these possibilities in mind, a diligent defense attorney may be able to convince the court to exclude a blood test by demonstrating that it does not meet the strict standards required to ensure accuracy. Your defense lawyer can ask the judge handling your case to disallow blood test results if presented with evidence that law enforcement officials or the medical professionals in charge of administering the test failed to strictly adhere to proper procedure.

Related: How to Beat a DUI

How Do We Challenge a Blood Test?

There are several ways to successfully challenge the results of a blood test.

  • The blood draw was not conducted by a qualified person.  Your blood must be drawn and sent to the lab by a trained medical professional. If your lawyer finds that the person who took your blood sample was unqualified to do so, your blood test may be thrown out by the court.
  • Errors in labeling. Close review of the evidence in your case may reveal something as simple as a labelling mistake on your blood sample that can call the accuracy of the evidence into question.  In the event of such an error, the result of the blood test may be thrown out by the court.
  • Improper storage procedures. Failure to quickly and properly store blood samples can cause elevated error rates. The bacteria, sugar, and yeast in your blood can begin to ferment when incorrectly stored and result in inaccurate evidence of intoxication.  Chemical analyses taking place on samples in which this has occurred can return a higher blood alcohol level than if the sample had been stored following correct procedure.  By questioning the lab technicians who handled your sample and reviewing paper evidence, your lawyer may be able to demonstrate a failure to properly store your blood sample.
  • Inaccurate results from testing errors. A failure to maintain laboratory equipment used to process blood samples can greatly increase the margin of error in this type of drug test.  If your lawyer can demonstrate that the lab equipment was not calibrated and maintained as it should be, the results of your test may be called into question.  This may result in the test being removed as evidence from your case. 
  • A break in the chain of custody. Possession of your blood sample is to be limited through the chain of custody.  This strict protocol is in place to prevent tampering with evidence.  If your defense counsel can demonstrate that the chain of custody requirements were broken at any time, your sample may be considered tampered with, and the court may suppress it as evidence.

If you have been accused of drunk driving, driving under the influence of cannabis, or another form of DUI, your best bet is to immediately seek legal counsel.  With experience in handling thousands of DUI, criminal, and traffic matters from both sides of the legal spectrum, Alexander Ktenas has the defense experience to offer you the best defense possible for your situation.  Call an experienced DUI attorney at (630) 425-0250 to set up a free consultation and start building your defense.