Critics of public-sector unions are banking that the Supreme Court's recent rulings indicate that a majority of the justices want to radically change labor laws covering whether government workers can be forced to pay union dues and just haven't been given the right case yet.

A recent brief filed by the plaintiffs in the case of Janus v. American Federation of State, County and Municipal Employees heavily cites decisions made by the court in the last seven years to argue that public-sector unions should not have the right to force government workers to pay them regular "security fees." The justices agreed in late September to hear the case, which involves whether Illinois state government worker Mark Janus can be forced to financially support AFSCME, the union that represents the agency where he works.

Janus is being represented by the National Right to Work Legal Defense Foundation. His attorneys heavily cite the Supreme Court in its 2014 Harris v. Quinn ruling, its 2012 Knox v. Service Employees International Union case, and 2010 Citizens United case in their brief filed Wednesday. In the brief, attorneys argue that the justices have made clear that a 1977 precedent called Abood v. Detroit Board of Education allows the fees must be overturned.

"Harris identified why Abood is poorly reasoned: A line cannot be drawn between [collective] bargaining with government and lobbying the government over its policies," Janus' lawyers argued.

The case could have major repercussions for organized labor. More than half of the movement, an estimated 7 million people, are in public-sector jobs. Security fees are a common provision in public-sector union contracts. Unions such as AFSCME count on those fees as a major source of revenue.

An internal 2015 survey by the union found that only one-third of their members would voluntarily pay dues no matter what and half of its membership couldn't be counted upon to do that. A minority of 15 percent would be certain to opt out of paying dues.

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 Abood. Last session, the justices appeared to be on the verge of overturning Abood in a case called Friedrichs v. California Teachers Association, but Justice Antonin Scalia's death resulted in a 4-4 deadlock.

Janus' case raises similar issues and his lawyers refer to the Friedrichs case, noting, "That question [in that case] is just as worthy of the court’s consideration today. Agency fees remain the largest regime of compelled speech in the nation." The fees run afoul of the First Amendment, they argue, because they force Janus to support political speech he opposes because "bargaining with the government is indistinguishable from lobbying government."

The lawyers note that during the most recent labor contract negotiations, AFSCME opposed changes that Illinois Gov. Bruce Rauner wanted to make, such as instituting merit pay for employees who do not take time off. By forcing Janus to fund AFSCME's bargaining efforts, the Abood precedent was forcing him to back lobbying that may not have been in his own best interest.