The U.S. Supreme Court has agreed to hear a retaliation lawsuit that seeks to answer a seemingly simple question: What does it mean to “file a complaint”?

That question lies at the heart of Kasten v. Saint-Gobain Performance Plastics Corp., a case in which a Wisconsin factory worker claimed he was unlawfully fired after verbally complaining to his bosses about the placement of time clocks. The employer argued that only written complaints — not oral ones — are protected activity under the anti-retaliation provision of the Fair Labor Standards Act. The 7th U.S. Circuit Court of Appeals agreed in July 2009.