In a referendum, 67.5% of voters opposed the law and only a smattering of counties voted to enact it. The law would have weakened unions at a time when the ability to organize is under attack at the federal level. Here’s what you need to know.

What was the law?

In 2017 Missouri’s Republican-led legislature passed a so-called “right-to-work” law that would allow private-sector workers to opt out of paying union dues. According to the National Right To Work Legal Defense Foundation, 27 states have similar laws, including Alabama, Indiana, Nevada, and Virginia. Proponents argue that compelling an individual to join a union curtails his or her freedom, particularly freedom of speech, and that such laws are good for a state’s economy. Opponents argue that these laws weaken unions and, as the American Federation of Labor and Congress of Industrial Organizations (AFL-CIO) says, “tilt the balance toward big corporations and further rig the system at the expense of working families.”

Why was it on the ballot?

Although the Missouri law passed last year, labor groups succeeded in petitioning to put it to a state-wide vote. They gathered around 300,000 signatures—twice the number they needed—and later outspent proponents of the law by nearly 5 to 1 in the campaign. Missouri is now the first state to overturn right-to-work legislation by a referendum.

Why does it matter?

The rejection of this law stands in direct opposition to the Supreme Court ruling in Janus v. AFSCME earlier this summer that declared workers have a constitutional right not to pay union dues. That ruling applies to public-sector unions in the 22 states that did not have right-to-work laws—Missouri is now the 23rd state to which that ruling applies. As the first major fight over unions since the Janus decision, some see Missouri’s referendum as an indication of the public’s support for unions beyond the state’s borders.