In 1996, IMI Cornelius Remcor, Inc. (Remcor) (defendant) hired Janice Arres (plaintiff) as a human-resources administrator. In March 1999, the Social Security Administration (SSA) advised Remcor that 10 percent of Remcor’s employees had entered social-security numbers on their W-2 forms that were inconsistent with federal records. Arres, believing these employees to be aliens who lacked authorization to work in the United States, recommended that Remcor fire the employees. Remcor instead sought legal advice from the SSA and an attorney, ultimately deciding to ask the employees to review their W-2 forms and correct any errors. Arres believed that Remcor’s course of action was unlawful and refused to process any information provided by the employees in response to Remcor’s request. Remcor thereafter fired Arres. Arres sued Remcor, alleging that Remcor had fired her in retaliation for her refusal, and claiming that her discharge was in violation of Illinois law. The district court granted summary judgment to Remcor, and Arres appealed.