Posner On Unions

I was just checking out the Becker-Posner Blog and saw that Richard Posner--prominent, influential Federal Judge on the Seventh Circuit Court of Appeals, and Senior Lecturer at the University of Chicago--has this to say about unions:

"On whether unions promote efficiency, a commenter was correct to point out that unions can benefit members, but they do so but [sic] restricting competition among workers. While this may raise the wages of unionized workers, it harms nonunionized workers (as well as consumers). If because of unionization an employer's wage bill rises, its demand for labor will decline, which means that fewer workers will be employed. By the way, in response to another comment, the decline in unionization in the private sector seems to me better evidence that union-protected employment is less efficient than employment at will than a study would be. It is the real market test."

By the by, my recollection of studying Posner in law school is that he is all about everything being driven by economics, and specifically, "the market." Maybe somebody can correct me on that if I am mistaken.