…. use the case, Harris v. Quinn, to strike down laws in 26 states requiring teachers, police officers, firefighters and other public-sector employees to pay dues to the unions that negotiate contracts on their behalf, even if the workers don’t want to become union members. …

How bad could the Supreme Court decision be for unions? Consider that in the two years after [Wisconsin Gov. Scott] Walker ended compulsory union membership in his state, the American Federation of Teachers lost 65 percent of its statewide members and the National Education Association shrank by 19 percent. Other public-sector unions also took big hits, with revenue plunging by 40 percent or more.

Instead, the ruling was limited in scope, per AP:

WASHINGTON (AP) — The Supreme Court dealt a blow to public sector unions Monday, ruling that thousands of home health care workers in Illinois cannot be required to pay fees that help cover the union’s costs of collective bargaining.

In a 5-4 split along ideological lines, the justices said the practice violates the First Amendment rights of nonmembers who disagree with the positions that unions take.

But if this wasn’t the bombshell that some expected, it still could have major impact in California, where 400,000 state-paid in-home care workers are represented by the SEIU. This month, they’ve been celebrating a huge victory. The state budget for the fiscal year starting Tuesday for the first time allows them to receive overtime.

But we can expect efforts prompted by today’s Supreme Court ruling to get these workers to opt in to union coverage. These efforts could well succeed. As the Wisconsin numbers cited by Politico show, a lot of union-represented workers don’t much like unions.