In the case of Kevin Kasten v. Saint-Gobain Performance Plastics Corporation, 2010, the U.S. Supreme Court had to decide whether an oral complaint about a violation of the Fair Labor Standards Act (FLSA) was protected under its anti-retaliation provision. The petitioner, Kevin Kasten, argued that he was fired from his job at Saint-Gobain Performance Plastics Corporation after orally complaining that the company's policy of not paying employees for time spent changing into and out of work clothes violated FLSA regulations. The court ruled in favor of Kasten with a majority opinion stating that FLSA’s anti-retaliation provision does indeed protect both written and oral complaints as long as they are sufficiently clear and detailed for a reasonable employer to understand them as an assertion of rights protected by statute.

In the dissenting opinion for Kevin Kasten v. Saint-Gobain Performance Plastics Corporation, Justice Scalia, joined by Justice Thomas, argued that the Fair Labor Standards Act (FLSA) does not protect employees from retaliation if they have only made verbal complaints about violations of the act. The majority held that both written and oral complaints are protected under FLSA's anti-retaliation provision. However, in his dissenting opinion, Justice Scalia contended that a strict interpretation of "filed any complaint" in Section 215(a)(3) should be applied which would exclude oral complaints from protection against employer retaliation. He also expressed concern over potential difficulties employers might face when trying to determine whether an employee’s informal grievance could legally qualify as “filing a complaint”. Thus he disagreed with extending protections to unwritten grievances or objections.