In an amicus brief filed this week, the American Civil Liberties Union of Illinois and five other nonprofit groups lent support to the case of four debtors who sued the city of Chicago for keeping their cars impounded even after they filed for bankruptcy.The case, City of Chicago v. Fulton, et al., was accepted by the U.S. Supreme Court in December. Oral arguments are scheduled for April 20.The question before the Supreme Court involves a stay provision of the federal Bankruptcy Code that allows for individuals who filed …