SCOTUS.
“Here is their logic: because unions cannot charge non-members for political activity and since non-members argue that everything a public-sector union does — even bargaining — is political in nature, it follows that any fees violate their First Amendment right not to pay for activity to which they object. Their target, in union parlance, is the “agency fee.”
They are exactly correct. Everything about public sector unions is political, because they operate entirely in the political arena.