But it is constitutional, the court added, to require nonmembers to help pay for the union’s collective bargaining efforts to prevent freeloading and to ensure “labor peace.”

The challengers in the new case, Janus v. American Federation of State, County and Municipal Employees, No. 16-1466, asked the court to overrule the Abood decision. All compulsory fees, they argued, violate the First Amendment because the subjects of labor negotiations between unions and the government are all matters of public concern.

Unions reject the First Amendment arguments, saying that collective bargaining is different from political activity. They said the plaintiffs were seeking to reap the benefits of such bargaining without paying their fair share of the cost.

Union leaders reacted to the court’s decision to hear the case with dismay bordering on alarm. “This case is yet another example of corporate interests using their power and influence to launch a political attack on working people and rig the rules of the economy in their own favor,” Lee Saunders, the president of the union in the case, said in a statement.

Mark Mix, president of the National Right to Work Legal Defense Foundation, which represents Mr. Janus, said he was pleased the court had agreed to step in.

”We are now one step closer,” he said in a statement, “to freeing over five million public sector teachers, police officers, firefighters, and other employees from the injustice of being forced to subsidize a union as a condition of working for their own government.”