Organized labor, already reeling from a potentially major financial hit thanks to a Supreme Court ruling last week that could result in millions of public-sector workers cutting off funding, could be subject to another blow from the justices: class-action suits from those workers seeking to get paid back from the unions.

In a little-noticed action, the Supreme Court invalidated a ruling last week by the 7th Circuit Court denying class-action certification in a case called Riffey v. Rauner. The case involved nonunion state-subsidized Illinois home healthcare workers seeking to be repaid the funds that for years they were forced to give to the union that ostensibly represented them.