The equal work, equal pay principle — under which workers should be equally treated in terms of wages and other conditions irrespective of their contract status if they engage in the same work — is one of the policies pursued by the government in its work-style reform agenda. The 2013 amended labor contract law stipulates that there should not be irrational disparities in the conditions of regular full-time corporate employees and people on irregular contracts such as part-timers, contract workers and temporary dispatch staff. In 2016, the government compiled a draft guideline on what kind of disparities between regular and irregular workers constitute irrational discrimination. As the number of people hired as irregular workers tops 20 million and accounts for nearly 40 percent of the nation's workforce, closing the pay gap between them and regular employees remains an urgent task.

The first top court decisions on a series of lawsuits filed across the country over claims of irrational treatment of workers on irregular status took place last week when the Supreme Court last week handed down rulings on two cases. From the viewpoint of plaintiffs, the decisions were mixed. In one of the lawsuits, filed by a man who works as a contract employee at a firm in Hamamatsu, Shizuoka Prefecture, the top court ruled that it's illegal for the company to deny the worker certain work-related allowances that are provided to regular employees on the grounds of his contract status.

But in the other case — involving three drivers at a Yokohama-based trucking company who were rehired on an irregular status after reaching retirement age and were suing the firm over cuts to wages and allowances even though they continue to engage in the same work as when they were hired as regular employees — the Supreme Court said the reduced pay cannot be deemed irrational, given that they were rehired following mandatory retirement.