On what grounds? That you weigh 160 lbs? Weight does influence the number of drinks your body can process but a .16 is high enough that you were likely impaired regardless of your weight. For a definitive answer consult an IL DUI lawyer.
In my opinion, your chances of a favorable outcome are much greater if you have an attorney. Hire someone local, and someone who appears often in the courthouse where your case will be heard. If your DUI was in Lake County, find a Lake County DUI attorney. And try to find someone who focuses their practice on DUI and other traffic laws. If you need any help, feel free to give me a call. I'd be happy to recommend an experienced DUI attorney I know. 1-800-517-1614.
