Katherine Born and Rick Gillispie were employed by a Blockbuster Video store in Iowa. Blockbuster maintained a policy that forbade dating between supervisors and their subordinates. Born and Gillispie were dismissed for violating the policy. They denied that they were romantically involved and filed suit for wrongful dismissal. Under Iowa law, an at-will employee can be discharged at any time for any reason, but Iowa law does recognize the public policy exception. To prevail in this lawsuit, what must the plaintiffs show about Iowa law?