In 1975, after vigorous campaigning by the United Farm Workers union, the state of California passed the Agricultural Labor Relations Act (ALRA), a pioneering self-help strategy granting farm workers the right to organize into unions. A quarter century later, only a tiny percentage of farm workers in the state belong to unions, and wages remain less than half of those of nonfarm employees. Why did the ALRA fail? One of the nation's foremost authorities...