Anti-union groups are making another major push in the U.S. Supreme Court to eliminate mandatory union dues, so-called “fair share” fees, for millions of public sector workers. This time, a full bench—if it takes the case—could end the deadlock that frustrated their efforts last year.

The latest attempt—Janus v. AFSCME—comes on the heels of the court's 4-4 divide in a nearly identical case—Friedrichs v. California Teachers Association. Before the death of Justice Antonin Scalia, the unions appeared headed for defeat in Friedrichs—with Scalia a likely vote against them. The views on the issue of Justice Neil Gorsuch, Scalia's successor, are unknown, but he may well hold the key to whether agency shop fees survive.

The stakes are high for unions. Agency shop fees are charged non-union members to cover the costs of collective bargaining by unions serving as the exclusive representatives of a workplace's employees. Political activities are excluded.