Everyone knows that drinking and driving is not a smart move. It's dangerous, illegal, and someone could get hurt or killed. Yet, in 2004, 50,147 people in Illinois were arrested for driving drunk. There's a fine line between being "okay to drive," and being DUI. How do you know when you've crossed it?

Illinois uses two criteria to determine if you are considered to driving while intoxicated (DUI) or not: Blood alcohol concentration (BAC) and degree of impairment. When a police officer suspects you of DUI, under Illinois law the officer can arrest you and take you to jail, where you will be asked to take a chemical test. If your blood alcohol concentration is above .08 percent, you are too drunk to drive, period. If a chemical test confirms a BAC of .08 or above, you will be charged with DUI. However, if your blood alcohol content is between .05 and .08, you may be charged with Illinois DUI if you exhibit additional evidence of impairment and intoxication. If your BAC is below .05, you are not considered DUI and you will be released from state custody without charges.

However, if the chemical test shows even a trace of drugs or other controlled substances, you will be charged with DUI no matter what your BAC is. It's important to note that many drugs stay in your system for days or even weeks. It doesn't matter to the Illinois police how long it's been since you've consumed these substances-you can be charged with an Illinois DUI if you give a police officer probable cause to arrest you and you test positive. Technically, someone who smokes marijuana occasionally could be arrested and charged with an Illinois DUI at any time over the next few weeks, until all traces of the drug have left the body.

Illinois also has enhanced penalties if you are especially drunk. If your BAC is over .16, you may be charged with Driving under the extreme influence instead of a regular Illinois DUI.  There are also special penalties if you have a child in the car with you or if you hurt someone else while driving drunk.

If you get convicted of an Illinois DUI, it's safe to say that the party is over. The penalties that you'll face vary depending on the circumstances of your arrest, your age and the charges against you. However, no matter what, they include significant fines, loss of driving privileges and possible jail time. Here are the penalties for various types of Illinois DUI charges: