From the Chicago Police Department:
The Chicago Police Department will conduct a DUI Strike Force Patrol in the Englewood(007th) District. The DUI Strike Force Patrol will commence at 8:00 p.m. on Saturday, July 28, 2012 and end at 4:00 a.m. on Sunday, July 29, 2012.
The purpose of this program is to saturate a pre-designated area with roving police officers that continually monitor vehicular traffic for signs of impaired driving. Patrols also place emphasis on speed, alcohol-related and safety belt violations. Police vehicles equipped for speed detection are deployed to apprehend speeding violators.
You can also be charged with any other traffic infraction that can be discovered in these roadblocks including driving without a license, or an expired license, or a suspended, or revoked license. Additionally, you, and your passengers (including those in the back seat) can be charged with failure to wear seat belts, and the driver can be charged with driving without insurance (even if the car is not yours).
It's a lot easier for you to avoid being charged in the first place than to have to hire an attorney.