Japanese labor law treats large employers differently from small employers, and union shop provisions are much less likely to be negotiated in small workplaces. For example, Chalmers cites 1979 data showing that 50 percent of all workplaces in Japan had a union shop provision. But while 73 percent of employers with more than 1,000 workers had such agreements, just 59 percent of employers with 500 to 999 workers did so. Some agreements are ambiguously worded, making their enforcement problematic. Other union shop provisions are tied to various requirements that the union promote "industrial peace", such as mandatory arbitration for all disputes and a relinquishment of the right to strike.