This past Thursday, the Wisconsin Senate passed a so-called “Right to Work” bill, leading to protests in the state’s capital.

What Is Wisconsin’s “Right To Work” Bill?

Once a union is recognized as the representative of a bargaining unit, that union is obligated to collectively bargain on behalf of all employees, not just union members. Because of this obligation, unions may require non-members to pay their share of the costs of collective bargaining and contract administration—known as “fair share” fees—as long as those fees don’t go toward other union functions such as political activity. The Wisconsin bill, like other states’ so-called “Right to Work” laws, would prevent unions from collecting these “fair share” fees from non-members.

Governor Scott Walker, a Republican who is widely expected to run for President in 2016, initially suggested this bill should not be a priority for the Senate, however, he has since announced that he will sign it. Twenty-four other states have adopted similar “Right To Work” laws, many in recent years, according to NPR. The New York Times reports that the bill introduced in Wisconsin is “is almost verbatim from a model provided” by the conservative advocacy group the American Legislative Exchange Counsel (“ALEC”).

The bill passed the Republican-controlled Senate by a vote of 17-15. The debate on the bill was contentious, and included eight hours of hearings under the Senate’s “fast-track” procedures and multiple interruptions by opponents of the bill yelling from the gallery. It is expected to pass the state Assembly, which is also controlled by Republicans.

Thousands of workers have rallied in the state capitol in protest. Although these protests have garnered significant press coverage, they are far smaller than the estimated 60,000 protesters who gathered in 2011 to protest Governor Walker’s actions against public sector unions.

What Was Wisconsin’s 2011 Fight Over Public-Sector Unions?

In February of 2011, Governor Walker gained national attention by aggressively supporting his proposed bill to strip public-sector unions of their ability to collectively bargaining. That bill ultimately passed, after weeks of procedural maneuvering on all sides—the Democrats in the state Senate left the state in an attempt to deprive the Senate of a mandatory quorum; the Republicans altered the bill so that they would not need a quorum to hold the vote. At the time, there were massive protests in Wisconsin, including some attended by approximately 60,000 people.

That bill limited the topics on which most public-sector unions could bargain to only salaries, which are usually set by statute anyways. Public-sector unions could no longer bargain over job protections, healthcare or benefits, training, job protections, or any other topic. It also limited existing civil service protections for state employees, among other changes. That bill exempted law enforcement unions.

The controversy led to a recall election against Governor Walker and several state legislatures in 2012. However, Governor Walker easily survived the recall.