Story highlights The term will begin Monday

Case concerns employee who says fees unfairly go to political activities

Washington (CNN) A week before the Supreme Court is set to begin the new term, justices announced Thursday that they are adding a big public sector union fees case to an already blockbuster docket.

The issue concerns something that deeply divided the court in 2016: whether non-members of public sector unions can be required to pay so-called "fair share" fees germane to collective bargaining.

The case is brought by Mark Janus, an Illinois public sector employee, who says the fees violate his First Amendment rights. Court precedent holds that while a non-member does not have to pay fees that go to political activities, that exemption does not include fees for issues such as employment conditions and employee grievances.

Unions fear the court might overrule that precedent which would be a big blow to their coffers at a time when union membership is already on a decline.

The high court voted to take up a similar case back when Justice Antonin Scalia was still alive, but he died before the case was decided. The justices ended up splitting 4-4 on the issue automatically affirming the lower court's opinion that went in favor of the unions.

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