Driving Under the Influence (DUI, DWI, drunk driving) in Illinois is illegal under several different scenarios. You can be charged with organic DUI, or in other words, DUI based upon proof of alcohol impairment. This is shown by the police officer's observation of your actions and conduct from the moment you are stopped to the time he releases you at the jail.
These garden variety observations for signs of a possible Illinois DUI arrest include how to conduct yourself leading up to the stop. Covered here would be how quickly you pulled over, your maneuvers while pulling over and your parking.
The officer would also observe your performance before exiting the vehicle. Here the police would be looking for any difficulties in retrieving your drivers' license, insurance card and registration. It would extend to your ability to follow his instructions, to engage in a cogent conversation and to understand your location and surroundings. Finally, your speech, the condition of your eyes and your general physical appearance would come into play.
The next step in the observations is the so-called exit sequence. That would cover things such as any assistance you required in stepping out of the vehicle and in walking to the squad car. Moreover the officer would take your balance and coordination into account.
After these general observations, the officer will ask you to submit to Standardized Field Sobriety Tests. These would include the Horizontal Gaze Nystagmus, the Walk-and-Turn and the One-Legged Stand. Following those, the officer will request you to provide a breath sample in the Preliminary Breath Test (PBT) device.
The officer will subsequently arrest you for DUI and take you to the jail. Here you will be asked to take a chemical test (the "official" breath test-the PBT does not count). If you agree to take this test and register a Blood Alcohol Level (BAL) of at least .08, you will be charged with a "per se" (automatic) DUI based only upon the BAL reading without there be any need to prove you are actually under the influence.
The police also have the option of requesting a blood test. The choice of which test to use is the officer's alone.
A blood test comes into play when there has been a crash and the driver is unconscious dead or otherwise incapable of refusing to provide a chemical test to determine the BAL. In this case, the driver, who must otherwise consent to giving a blood or breath sample, is presumed to have given consent to a blood test. 625 ILCS 5/11-501.6
This is known as "implied consent". The law entertains the legal fiction that when you accept a driver's license, you unknowingly consent to giving a blood test if you are unconscious.
A driver who is taken to an emergency room will typically give blood at the hospital for the purpose of the doctor providing treatment. The results of this test are admissible in the DUI prosecution even if the driver is capable of refusing. 625 ILCS 5/11-501.4
Absent a crash, police will not typically request a blood draw to determine your BAL. A breath test is faster and less expensive.
However, if the officer suspects drugs are a factor, a breath test is useless. If you do not consent to a blood or urine test, it will be very difficult for the state to prove that you were under the influence of drugs or had any amount of an illegal substance in your system.
What tools are available to the police in Illinois for proving a DUI charge? Illinois DUI Lawyer Blawg, January 11, 2013
If marijuana ever becomes legal in Illinois, would it be legal to drive high? Illinois DU Lawyer Blawg, November 30, 2012