On Friday, hundreds of striking teachers flooded the foyer of the West Virginia capitol building in Charleston. Holding signs that read “Whose side are you on?” they voted to occupy the building until their demands were met.

As the Supreme Court considers the Janus v. AFSCME case this very week — posing an existential threat to public sector unions throughout the country — labor movement activists should be watching the West Virginia teachers’ strike closely. The coincidence of the two events seems almost scripted: as Janus promises to gut the legal framework for public sector worker organizing, West Virginia teachers are militantly flouting the law.

Many in the labor movement contend that this level of rank-and-file engagement is the key to surviving right to work. The question is, how does a militant mood in a workforce like West Virginia’s teachers come into being? Finding the answer in this case requires paying attention the central demand that caused workers to defy union leadership and embark on one of the largest wildcat strikes in recent American history: adequate health care.