While much of Justice Alito’s majority opinion dealt with the fine contours of speech related to unions, it did have a brief discussion on compelled speech:

As we explained in Knox, “[t]he government may not prohibit the dissemination of ideas that it disfavors, nor compel the endorsement of ideas that it approves.” 567 U. S., at ___ (slip op. at 8–9); see also, e.g., R.A.V. v. St. Paul, 505 U. S. 377, 382 (1992); Riley v. National Federa­ tion of Blind of N.C., 487 U. S. 781, 797 (1988) West Vir­ ginia Bd. of Ed. v. Barnette, 319 U. S. 624 (1943); Wooley v. Maynard, 430 U. S. 705, 713–715 (1977). And “com­ pelled funding of the speech of other private speakers or groups” presents the same dangers as compelled speech. Knox, supra, at ___ (slip op. at 9). As a result, we ex­ plained in Knox that an agency-fee provision imposes “a ‘significant impingement on First Amendment rights,’” and this cannot be tolerated unless it passes “exacting First Amendment scrutiny.” 567 U. S., at ___ (slip op. at 9–10).