Anti-union organizations, building on last year's successful challenge to public-sector union fees, have returned to the U.S. Supreme Court with three new challenges to the operations of organized labor.

The new petitions are part of what lower courts have begun to call “clean-up proceedings” in the wake of the Supreme Court's 5-4 decision last term in Janus v. AFSCME. In Janus, the conservative majority, led by Justice Samuel Alito Jr., overruled a four-decade-old precedent that said unions could impose “fair share” fees on nonmembers for the cost of collective bargaining.

“At the time of this writing, there are at least 35 class action lawsuits pending in 18 federal district courts that seek to require unions to return just a small portion of those billions of dollars in unlawfully seized union fees,” one of the petitioners told the justices.