The appellate court decided that no reasonable prosecutor--or person, for that matter--could have thought a parody character called Junius Puke at a Web site called The Howling Pig was a sound basis for criminal action.

Milan lost an estimated $100 million in a complex interest rate swap deal that it made with four banks in the run-up to the financial crisis. But the city fought back, becoming among the first municipalities to file criminal fraud charges against the banks under an Italian law that lets prosecutors file quasi-criminal charges against companies and their managers.