On Feb. 26 the U.S. Supreme Court will consider dealing what would likely be a devastating blow to America’s already-struggling labor movement. The issue before the court is whether it’s unconstitutional to require government workers to fund unions that represent them. Public sector employees now represent around half of union members in the U.S., and without money from members the organizations wouldn’t be able to fund themselves. After decades of declining membership—driven in part by state-level legislative attacks—the fight over...