In a ruling issued on Friday, a three-judge panel of the U.S. Court of Appeals for the Seventh Circuit held that a U.S. District Court judge had erred in finding that the law violated the Constitution's equal-protection clause by requiring some public-employee unions but not others to hold annual recertification votes.
The state law, passed in early 2011 after bitter protests at the Wisconsin Capitol, exempted from the annual recertification requirement and some other provisions the state's unions representing the police, firefighters, and other public-safety workers. The exemption was based on the belief that the state could not risk the potential societal costs of labor unrest among crucial public-safety workers.
The unions challenging the law argued that it had identified those unions involved in public safety in a manner that appeared arbitrary, counting among them motor-vehicle inspectors but not, for example, campus police officers at the University of Wisconsin.
In the decision it issued on Friday, however, the Seventh Circuit panel held that it would be overstepping its powers if it were to second-guess how a state legislature had gone about distinguishing between certain categories of public employees.
A Wisconsin state judge struck down the recertification requirement in a September 2012 ruling that is being appealed.