The Supreme Court, for the first time, ruled in favor of a corporate whistle-blower late last month. Mr. Masaharu Hamada, an employee at Olympus Corp., had filed suit after being demoted, forced to take rudimentary tests, ignored by colleagues and given cold treatment after raising complaints about business practices. After a five-year legal battle, Mr. Hamada's experience at Olympus was ruled unfair retaliatory treatment.

The victory is more than Mr. Hamada's alone; it offers an opening for companies to change how they handle employees and how they accept criticism.

During those five years, Mr. Hamada had to remain an employee of Olympus, since Japanese law only allows current employees to pursue such legal action. Before filing suit, Mr. Hamada first went to his bosses and then to the company's corporate compliance division to raise questions about complaints from a supplier that Olympus was luring away the supplier's employees.