Issues in the case -- brought by the Madison teachers union and a local Milwaukee municipal employees union -- include whether or not the law is constitutional in the way it applies to local teachers' union across the state and to all municipal or village employees represented by unions.
Attorney General J.B. Van Hollen argues that Act 10 doesn't violate the right of any employees, union or not, to associate together and ask their employers for increased wages or for changes in working conditions.
Attorney Lester Pines, representing the unions, said Act 10 effectively does violate such rights because it forces unions to have annual reelections that require a super-majority, and prevents unions from deducting wages from employee pay checks to fund their work.
The court could decide soon to rule on one of the issues that allow the state to begin carrying out the annual union re-certification elections in school districts and towns and cities across the state.
Questions from the justices on Monday suggested that there is a four-vote majority of conservative justices who still strongly support Act 10. The most critical questions for Van Hollen came from the two more liberal justices on the court, Chief Justice Shirley Abrahamson and Justice Anne Walsh Bradley.