SPRINGFIELD — Gov. Bruce Rauner is pleased that the U.S. Supreme Court will decide whether non-union state employees must pay “fair share” fees to cover bargaining costs.

The high court announced Thursday it will hear an Illinois case by Mark Janus. The child-support specialist says that forcing him to pay union fees violates his First Amendment rights. The defendant in the case is the American Federation of State, Council and Municipal Employees Council 31.

Republican Rauner says employees “should not be forced to give up a portion of their pay each month to fund public-sector union activity.”

Rauner says his 2015 executive order prohibiting state-agency “fair share” collection set the Janus case in motion.

An AFSCME statement calls the case a plan to “rig the economic rules against everyday working people.”

The case is going before a Supreme Court with a reconstituted conservative majority, creating the potential to financially cripple Democratic-leaning labor unions that represent government workers. The justices deadlocked 4-4 in a similar case last year.

The court could decide to overturn a 40-year-old Supreme Court ruling that allows public sector unions to collect fees from non-members to cover the costs of negotiating contracts for all employees.

The latest appeal was filed at the Supreme Court just two months after Justice Neil Gorsuch filled the high court seat that had been vacant since Justice Antonin Scalia’s death.

The stakes are high. Union membership in the U.S. declined to just 10.7 percent of the workforce last year, and the ranks of private-sector unions have been especially hard hit.

About half of all union members now work for federal, state and local governments, and many are in states like Illinois, New York, and California that are largely Democratic and seen as friendly toward unions.

About half of the states have laws covering so-called “fair share” fees that cover bargaining costs for non-members.

Janus is seeking to overturn a 1977 Supreme Court case, Abood v. Detroit Board of Education, that said public workers who refuse to join a union can still be required to pay for bargaining costs, as long as the fees don’t go toward political purposes. The arrangement was supposed to prevent non-members from “free riding,” since the union has a legal duty to represent all workers.

A federal appeals court in Chicago rejected Janus’ claim in March. Gorsuch was confirmed in April and the appeal was filed in June.

The justices will hear argument in the winter.