Harris v. Quinn, at bottom, represented differing views over the value of unions. Justice Alito seemed to doubt that a union’s ability to operate as a bargaining unit did not depend on collecting fees from non-members.

A union’s status as exclusive bargaining agent and the right to collect an agency fee from non-members are not inextricably linked.

Justice Kagan disagrees, strongly, and counters that a “different source” explains the “majority’s skepticism About Abood.”

Perhaps, though, the majority’s skepticism about Abood comes from a different source: its failure to fully grasp the government’s interest in bargaining with an adequately funded exclusive bargaining representative. One of the ma- jority’s criticisms of Abood, stated still more prominently in Knox, 567 U. S., at ___ (slip op., at 10–11), goes some- thing as follows. Abood (so the majority says) wrongly saw a government’s interest in bargaining with an exclusive representative as “inextricably linked” with a fair-share agreement. Ante, at 31; see ante, at 20. A State, the majority (a bit grudgingly) acknowledges, may well have reasons to bargain with a single agent for all employees; and without a fair-share agreement, that union’s activities will benefit employees who do not pay dues. Yet “[s]uch free-rider arguments,” the majority avers, “are generally insufficient to overcome First Amendment objections.” Ante, at 8–9 (quoting Knox, 567 U. S., at ___ (slip op., at 10–11)). In the majority’s words: “A host of organizations advocate on behalf of the interests of persons falling within an occupational group, and many of these groups are quite successful even though they are dependent on voluntary contributions.” Ante, at 33–34.

Kagan explains that this reasoning is in tension with decades of union-related caselaw:

But Abood and a host of our other opinions have ex- plained and relied on an essential distinction between unions and special-interest organizations generally. See, e.g., Abood, 431 U. S., at 221–222 and n. 15; Communica- tions Workers v. Beck, 487 U. S. 735, 750 (1988); Machin- ists v. Street, 367 U. S. 740, 762 (1961). The law compels unions to represent—and represent fairly—every worker in a bargaining unit, regardless whether they join or contribute to the union. That creates a collective action problem of far greater magnitude than in the typical interest group, because the union cannot give any special advantages to its own backers. In such a circumstance, not just those who oppose but those who favor a union have an economic incentive to withhold dues; only altru- ism or loyalty—as against financial self-interest—can explain their support. Hence arises the legal rule counte- nancing fair-share agreements: It ensures that a union will receive adequate funding, notwithstanding its legally imposed disability—and so that a government wishing to bargain with an exclusive representative will have a via- ble counterpart.

Kagan, with a nod to her favorite hunting partner, quotes Justice Scalia, who happened to vote in themajority:

As is often the case, JUSTICE SCALIA put the point best:

“Where the state imposes upon the union a duty to de- liver services, it may permit the union to demand re- imbursement for them; or, looked at from the other end, where the state creates in the nonmembers a le- gal entitlement from the union, it may compel them to pay the cost. The ‘compelling state interest’ that justi- fies this constitutional rule is not simply elimination of the inequity arising from the fact that some union activity redounds to the benefit of ‘free-riding’ non- members; private speech often furthers the interests of nonspeakers, and that does not alone empower the state to compel the speech to be paid for. What is dis- tinctive, however, about the ‘free riders’ [in unions] … is that … the law requires the union to carry [them]—indeed, requires the union to go out of its way to benefit [them], even at the expense of its other in- terests. . . . [T]he free ridership (if it were left to be that) would be not incidental but calculated, not im- posed by circumstances but mandated by government decree.” Lehnert, 500 U. S., at 556 (opinion concur- ring in judgment in part and dissenting in part).

And, in her closing section:

For many decades, Americans have debated the pros and cons of right-to-work laws and fair-share require- ments. All across the country and continuing to the pre- sent day, citizens have engaged in passionate argument about the issue and have made disparate policy choices. The petitioners in this case asked this Court to end that discussion for the entire public sector, by overruling Abood and thus imposing a right-to-work regime for all govern- ment employees. The good news out of this case is clear: The majority declined that radical request. The Court did not, as the petitioners wanted, deprive every state and local government, in the management of their employees and programs, of the tool that many have thought neces- sary and appropriate to make collective bargaining work. The bad news is just as simple: The majority robbed Illinois of that choice in administering its in-home care program. For some 40 years, Abood has struck a stable balance—consistent with this Court’s general framework for assessing public employees’ First Amendment claims— between those employees’ rights and government entities’ interests in managing their workforces. The majority today misapplies Abood, which properly should control this case. Nothing separates, for purposes of that decision, Illinois’s personal assistants from any other public em- ployees. The balance Abood struck thus should have defeated the petitioners’ demand to invalidate Illinois’s fair-share agreement. I respectfully dissent.