The National Labor Relations Act of 1935 authorized trade unions in the private sector to be established to represent employees in collective bargaining for wages and other benefits from employers.

[1] Since about 2006, with the appointment of Justice Samuel Alito, which gave the Court a conservative advantage, groups opposing agency fees, such as the National Right to Work Legal Defense Foundation, have brought cases challenging Abood.

These groups contended that within the public sector all union activities could be considered political, since they ultimately seek to influence government policy, and thus violate the First Amendment.

[2] In 2012, the Supreme Court ruled in Knox v. Service Employees International Union, Local 1000, 567 U.S. 298 (2012), which considered a "Temporary Special Assessment to Create a Political Fight-Back Fund" imposed upon a class of 42,000 State of California employees who were nonmembers, the Court held that a union had violated their rights by collecting fees in the absence of the notice and procedural requirements of Teachers Local No.

11-681, 573 U.S. ___ (2014), which considered the validity of an agency fee policy affecting home health care workers receiving public funds in the state of Illinois; the Court held that the health care workers were not public-sector employees and thus could not be required to pay agency fees.

... [A]s state and local expenditures on employee wages and benefits have mushroomed, the importance of the difference between bargaining in the public and private sectors has been driven home.

Rauner had run on an anti-union platform, and once in office, he issued an executive order that suspended collection of agency fees from non-union members who benefitted from a contract negotiated by the American Federation of State, County and Municipal Employees (AFSCME), which represented Illinois public sector employees.

Rauner used the decision from Harris to support these actions, arguing that agency-shop agreements violate nonmembers' right to free speech.

In May 2015, the District Court judge found that Rauner lacked sufficient standing to issue the challenge, as he had "no personal interest at stake."

A new complaint was filed by Janus and other plaintiffs, alleging that the fees they paid under an agency-shop agreement violated their First Amendment rights.

[14] Observers believed that based on the past deliberations, the decisions in Harris and Friedrichs, and Gorsuch's conservative jurisprudence, Janus would likely prevail before the Supreme Court.

Kagan criticized the majority opinion as one that "overthrows a decision [Abood] entrenched in this nation's law — and in its economic life — for over 40 years.

"[15] Justice Sotomayor wrote her own separate dissent, critical of the weight given to First Amendment protections that had been established in Sorrell v. IMS Health Inc., No.

Public-sector union officials predicted that they would lose 10 to 30 percent of their members and tens of millions of dollars in revenue in the states that would be affected.

[16][15] The nation's two largest public sector unions lost the vast majority of agency-fee payers after the ruling.