Labour union strategy and non-regular worker unionisation: an institutionally adjusted insider–outsider model for Japan

Japan’s unionisation rates and share of regular employees in the workforce have been in continuous decline since the 1970s. We use an insider–outsider model adjusted to Japanese employment institutions to link subjective short-term choice sets of unions with long-term institutional change. Non-regular work sets the entry conditions into the labour market, and by representing regular workers exclusively, unions protect wages and security for their members during economic downturns, without increasing involuntary unemployment at the national level. This strategy is linked to the observed expansion and diversification of non-regular work in Japan, particularly in involuntary non-regular employees who were originally seeking regular work. A rise in the non-regular worker base further reduces unionisation rates and union bargaining power, suggesting that the long-term exclusion of non-regular workers is unsustainable. We present a case study of UA Zensen, the major union federation leading non-regular worker unionisation at national level, to examine how union federations can overcome enterprise level barriers to expansion. Despite UA Zensen’s success, significant challenges to inclusive unionisation still exist, particularly in the manufacturing sector. Despite changes in union federations’ official stance in the late 1990s, the data show that non-regular workers continue to be excluded at enterprise level.