Walter Williams talks about nullification as a guest host on the Rush Limbaugh show, 02-28-11

“The states are beginning to get some gets – in terms of doing something that the founders would have surely supported…and that is the doctrine of state nullification.”

“I support states nullifying unconstitutional practices by the federal government.”

More reading:
Current State nullification efforts

USA Today article, quoting Tenth Amendment Center’s Michael Boldin, cited by Walter Williams