The Cook County public guardian wants a nonprofit to turn over its case study of an infant who died after her family received counseling services from the agency. But the agency is asking the Illinois Supreme Court to exempt the report from discovery and, in the process, create a rule that allows similar accounts to remain behind a veil. Both sides made their cases to the state’s top justices in oral arguments last week. In 2009, the Department of Children and Family Services received a complaint alleging …