Free-market groups are asking the Supreme Court to again take up the issue of whether public-sector employees can be forced to contribute to a union as a condition of employment.

The justices deadlocked 4-4 on a similar case last year following Justice Antonin Scalia's death, leaving the question unresolved by the court. Now that Justice Neil Gorsuch has replaced Scalia, the court may decide to take it up again.

The case, called Janus v. American Federation of State, County and Municipal Employees, asks whether an Illinois state government employee can be forced to pay a so-called "security fee" to the union as a condition of employment. Such fees are common provisions in public-sector union contracts. Losing them would be a severe financial blow to the unions.

The plaintiff, Illinois Department of Healthcare and Family Services worker Mark Janus, argues the fee violates his First Amendment rights because he doesn't support the union and doesn't want to subsidize its activities. "I went into this line of work because I care about kids. But just because I care about kids doesn't mean I also want to support a government union. Unfortunately, I have no choice. I'm filing this case on behalf of all government employees who want to serve their community or their state without having to pay a union first," Janus said.

Unions argue that they are owed the fees to compensate for their collective bargaining on behalf of the workers. The Supreme Court ruled that such fees were legal in a 1977 case called Abood v. Detroit Board of Education. However, the court under Chief Justice John Roberts has indicated it is willing to revisit the issue. Last session, the justices appeared to be on the verge of narrowly overturning Abood in a case called Friedrichs v. California Teachers Association. Scalia's death is widely believed by court watchers to have prevented the court from ruling 5-4 to overturn the Abood precedent.

Janus is being represented by the National Right to Work Legal Defense Foundation and the Liberty Justice Center, nonprofit groups that advocate against such "forced unionism."

"Requiring public servants to subsidize union officials' speech is incompatible with the First Amendment. This petition asks the Supreme Court to take up this case and revisit a nearly half-century-old mistake that led to an anomaly in First Amendment jurisprudence," said Mark Mix, president of the National Right to Work Legal Defense Foundation.

Organized labor and its allies in the Democratic Party have been bracing for a major hit to union power since Gorsuch was confirmed. "This justice is poised to cast the fifth vote to make it next to impossible for public-sector labor unions to organize," said Tom Perez, chairman of the Democratic National Committee and former secretary of labor, in an April speech to the United Steelworkers union.

Another case, Yohn v. California Teachers Association, which makes the same argument against the union fees, may be taken up the Supreme Court this year. The plaintiff in that case is being represented by the Center for Individual Rights, the libertarian nonprofit that argued the Friedrichs case before the high court.