In Illinois, operating under the influence (OUI) is a Class “A” misdemeanor for the first offense. It is punishable by a maximum of six months to one year in jail and/or up to $2,500 in fines. And, it is very likely your previous dui WILL matter. Illinois has heightened its attention to boating/ operating under the influence recently. It is possible that your past dui will result in an increased mandatory sentence based on the previous conviction. It is important you seek legal counsel on this matter immediately to ensure an adequate defense may be prepared.