When the government-employee unions lost at the Supreme Court in Janus v. American Federation of State, County and Municipal Employees last week, the court’s ruling was primarily about the freedom of speech — particularly, the freedom from compelled speech.

Beyond its implications for free-speech jurisprudence, Janus, which ruled that non-union members couldn’t be forced to pay partial union dues known as “agency fees,” could have serious effects on union membership. Anyone trying to predict the effects ought to look to Wisconsin, and the aftermath of Gov. Scott Walker’s Act 10.