This November, California voters must decide two policy questions of great concern to public-sector unions. One is a tax hike to stave off further cuts to state spending (there are two versions on the ballot with a chance of passing). The other is a "paycheck protection" measure that would ban the practice of unions' deducting money from…

At first glance, public-sector labor unions are just one of many types of organizations that participate in the political process. However, these unions differ significantly from other interest groups made up of individual citizens or non-labor organizations. Because their members' interests are tied to government policy, these unions are more…