220 ILCS 5/5-110

Disclosure of customer information to law enforcement agencies. A public utility shall not disclose customer record information to a law enforcement agency unless the law enforcement agency requests the customer record information in writing, specifying that the information is necessary for a law enforcement purpose. Customer record information includes, but is not limited to, social security numbers, public aid numbers, and employment data. Nothing in this Section shall affect the Commission's access to information under this Act or any other law.