Actually, it might be time to retire the term “Big Labor” after the Supreme Court decision in Janus v AFSCME. As the Washington Post points out today, the existential crisis facing public-employee unions is just how big they’ll be now that compulsory agency fees have been ruled unconstitutional. The prospects are grim indeed, as recent experience in Wisconsin has shown:

Some of the nation’s largest and most powerful unions are bracing for an exodus of members and a substantial financial hit after a Supreme Court decision that threatens their ability to collect fees, a ruling expected to severely diminish organized labor’s political strength and undermine its capacity to represent worker interests.

Let’s parse this out for a moment. Note well the order in which the diminishment is cast — politics first and ostensible function second. That’s an accurate portrait of PEU priorities, too, which is one reason Mark Janus sued AFSCME in the first place. Unions have argued that agency fees only cover collective bargaining, not their political activities. If that’s the case, then their loss should only impact worker representation, not “political strength.” And yet everyone knew that was a threadbare lie.

Now that the floodgates are open, how may will join the outbound tide? Two key teachers’ unions are warning of substantial losses, but their estimates are almost certainly too optimistic:

The National Education Association — the nation’s biggest union, with more than 3 million teachers — said it fears losing about 200,000 members this year and possibly 100,000 more next year. It, along with other public-sector unions, has worked to aggressively recruit and retain members, sometimes by having them sign pledge cards and providing professional development for new teachers. …

American Federation of Teachers President Randi Weingarten said she is encouraged by the number of teachers who have affirmed their membership in recent months, with recommitment rates of up to 95 percent in some places. Out of 1.7 million members in that union, roughly 80,000 are nonmembers who pay fees. Weingarten could not project the financial impact of losing that population but hoped to have an estimate once the union finalizes its budget next month.

And those might hold up … for a while. For one thing, the number of non-members is probably not going to serve as a long-term indicator of retention. The difference between paying agency fees as a nonmember and paying full dues to get some benefits from membership is probably not significant enough to have many choosing the former, especially in closed-shop environments with compulsory payments and opt-out procedures. Now that people have to choose to opt in on agency fees, how many of those will continue to do so, and how many “members” will let their membership lapse?

We have some data on that from Wisconsin, as noted above. Four years after Scott Walker and Republicans in the legislature passed Act 10, which eliminated compulsory dues and agency fees and imposed an opt-in policy, membership dropped by a lot more than what NEA and AFT hope now:

Union officials declined to release precise membership data but confirmed in interviews that enrollment is dramatically lower since the new law was signed in 2011.

The state branch of the National Education Association, once 100,000 strong, has seen its membership drop by a third. The American Federation of Teachers, which organized in the college system, saw a 50 percent decline. The 70,000-person membership in the state employees union has fallen by 70 percent.

Once people figure out that they don’t have to pay the unions, they’ll stop paying agency fees, and eventually membership fees altogether. It doesn’t take a genius to figure out that workers aren’t going to shell out monthly dues to an organization which pays more attention to Nancy Pelosi and Chuck Schumer than their own members, not without being forced to do so. That’s why the compulsory payment regimes set up by states were so important to the unions in the first place. Now that Janus has overturned them, they have an existential crisis on their hands.

Can unions fix that problem? Sure, but it entails prioritizing membership before politics. To the extent that their politics distracts from that, and perhaps to the extent that their politics alienates workers, their base will continue to erode. The incentives will shift to customer service rather than national politicking, so even if they manage to become Medium Labor, their political impact will get necessarily blunted by the need to focus resources on making membership valuable enough to retain. That’s what happened in Wisconsin and Michigan, both of which went to Donald Trump in 2016 as a key part of his stunning victory over Hillary Clinton. (It didn’t help that Hillary seemed clueless as to the need to organize effectively in those states, either.)

Either way, the change will be transformative — and Democrats will have to look elsewhere for its organizing strength. They’re the ones who will feel the biggest political impact of Janusgeddon.