100 years ago, if you were an industrialist who wanted to keep unions out of your plant, you hired the Pinkerton detective agency to infiltrate the unions and, if necessary, bust some heads. Today, corporations employ more subtle, but perhaps more effective strategies  to prevent their workers from organizing.  Law firms such as Ogletree Deakins and IRI Consultants have worked not only with high-profile corporations like Google and Ikea, but also with nonprofits like the ACLU of Kansas, to block union drives among their employees.  John Logan is a professor and the director of labor and employment studies at San Francisco State University who has studied modern-day union-busting outfits.