The Wisconsin Supreme Court on Monday heard arguments on the constitutionality of a 2011 law that all but eliminated collective bargaining for most public employees.
The law, which prompted large protests and thrust the Republican administration of Gov. Scott Walker into the national spotlight, has divided the state along partisan lines for more than two years. The latest battle has centered largely on a broad legal question: Can state lawmakers so significantly curtail collective bargaining that union membership is made less desirable?
“I don’t believe the two ships pass in the night,” J. B. Van Hollen, the attorney general of Wisconsin, said when asked by a judge about the dueling legal theories. “I believe they collide.”
Mr. Van Hollen argued that group bargaining was not a constitutional guarantee but rather a “benefit” permitted by lawmakers. He added that he believed state officials had a “bigger ship” and would win in the end.
The law, which led to a failed attempt to remove Mr. Walker from office last year, has been challenged by a teachers union in Madison and by a labor group representing employees of the city of Milwaukee. Both plaintiffs contend that the measure violates freedom of association rights and equal protection of the law by subjecting unionized public employees to burdens not faced by their nonunion colleagues.
“If you are an employee and you choose to associate in this activity, you will be...