Like many states, California permits unions to represent public sector employees. But employees may "opt out" of paying dues toward these unions' political activities.To permit the "opt out," the unions must issue what are known as "Hudson" notices at least annually, which advise employees of how much of their dues are spent on collective bargaining and how much on political and other non-representative activity. The employees can opt-out of paying the fee not that are not allocated to collective bargaining -related activities. Unions are permitted to rely on the prior year's ratio to set the current year's dues.
This system exists because of the First Amendment. The public sector employer would not be able to force employees to join an organization that requires financing of viewpoints with which the employee does not agree.
So far so good? Well,what if the union issues a Hudson notice, and then a few weeks after the "opt out" period, issues a special fees increase after issuing its Hudson notice? Can it unilaterally do this without a new notice? That was the issue the Supreme Court confronted in Knox v. SEIU, Local 1000.
The Supreme Court said, "no":
To respect the limits of the First Amendment, the union should have sent out a new notice allowing nonmembers to opt in to the special fee rather than requiring them to opt out. Our cases have tolerated a substantial impingement on First Amendment rights by allowing unions to impose an opt-out requirement at all. Even if this burden can be justified during the collection of regular dues on an annual basis, there is no way to justify the additional burden of imposing yet another opt-out requirement to collect special fees whenever the union desires.
Why?
Public sector unions have the right under the First Amendment to express their views on political and social issues without government interference. . . .But employees who choose not to join a union have the same rights. The First Amendment creates a forum in which all may seek, without hindrance or aid from the State, to move public opinion and achieve their political goals. “First Amendment values [would be] at serious risk if the government [could] compel a particular citizen, or a discrete group of citizens, to pay special subsidies for speech on the side that [the government] favors.” ... Therefore, when a public-sector union imposes a special assessment or dues increase, the union must provide a fresh Hudson notice and may not exact any funds from nonmembers without their affirmative consent.
5 justices joined the majority opinion. 2 justices concurred in the judgment, agreeing the union needs to secure consent from the non-members. 2 justices dissented, and would hold that the union gets to set its non-member contribution rate based on the prior year's expenses, even if the union imposes a special assessment immediately thereafter.
The case is Knox v. SEIU, Local 1000 and the opinion is here.