Richard B. Freeman and James L. Medoff's now classic 1984 book What do unions do? stimulated an enormous theoretical and empirical literature on the economic impact of trade unions. Trade unions continue to be a significant feature of many labour markets, particularly in developing countries, and issues of labour market regulations and labour institutions remain critically important to researchers and policy makers.

The relations between unions and management can range between cooperation and conflict; unions have powerful offsetting wage and non-wage effects that economists...