Collective bargaining rights of public employees in Wisconsin were restored Monday in a ruling by Dane County Judge Jacob Frost.

Public employee unions largely lost their ability to collectively bargain in 2011 with the passage of Act 10.

Here's a look back at the origins of Act 10 — and the possibility of Frost's ruling being challenged and ending up before the Wisconsin Supreme Court:

What is Act 10?

Shortly after being elected governor in November 2010, Scott Walker introduced what would become his signature piece of legislation, essentially ending collective bargaining rights for public employee unions in Wisconsin.

Act 10 ended the ability of most public-sector unions to negotiate over any issues other than raises, and those raises were capped at the rate of inflation. In addition, unions were required to hold annual elections to maintain their ability to negotiate for those raises. For those elections, they must win a majority of all eligible members, not just those who cast votes.

The measure cut public workers' paychecks and siphoned off most of the strength of their unions.

Public workers earning $50,000 a year saw their take-home pay shrink by about 8.5% because they had to pay more for their benefits, according to an analysis by the nonpartisan Legislative Fiscal Bureau at the time.

How much money did Act 10 save taxpayers?

PolitiFact Wisconsin previously checked Walker’s claim that Act 10 has “saved the taxpayers some $3 billion." We rated that quote, from summer 2014, Mostly True.

At that point, there had been about $2.35 billion in savings associated with retirement and about $682 million associated with health insurance — though that incomplete number leaves out municipalities.

When public employee unions launched the lawsuit last November, Republican lawmakers cited an estimate that Act 10 has saved Wisconsin taxpayers over $16.8 billion.

PolitiFact Wisconsin investigated that claim and found that number came from the MacIver Institute, a conservative think tank. That number fell in line with previous reports and studies from other groups, though little research has been conducted on the subject in the past two years.

And as previously noted, the costs didn’t simply disappear. Rather, they were transferred from other taxpayers to public employees, who also pay taxes and now pay a higher share of their retirement funding and health-care costs.

More: Labor unions, politicians in Wisconsin respond to decision overturning Act 10, look ahead

How did Frost justify overturning Act 10?

Act 10 immediately affected public school teachers' unions. It also ended unions at UW Health. It didn't, however, unilaterally apply to public safety employees, a point noted by Frost.

"Rational basis review provides a simple premise," Frost wrote in a July ruling that denied a motion filed by the Republican-controlled Legislature to dismiss the case. "Can you explain a law’s differing treatment of different groups in a way that makes sense and supports a public policy? If not, the different treatment is irrational and violates the right to equal protection of the laws.

"Because nobody could provide this Court an explanation that reasonably showed why municipal police and fire and State Troopers are considered public safety employees, but Capitol Police, UW Police and conservation wardens, who have the same authority and do the same work, are not."

That unequal treatment of public safety employees remained at the heart of Frost's ruling Monday.

How did lawmakers and the public respond to Act 10?

Walker announced his plan to curb union rights in February 2011. He believed he would be able to push the legislation through the GOP-controlled Legislature in a week. Democratic lawmakers foiled his plan by heading to Illinois to delay a vote.

In their absence, tens of thousands of people protested at the Capitol daily.

In March, Democrats returned to Madison and a vote approving the legislation that would become known as Act 10 would pass the Legislature and was signed into law. Act 10 took effect in June 2011.

Consequently, Walker, Lt. Gov. Rebecca Kleefisch and 13 state senators faced recalls over Act 10 — 10 Republicans and three Democrats. Most incumbents won, but Democrats managed to unseat three Republicans. That was enough to give them control of the Senate in summer 2012, but the victory came when the Legislature was out of session and was short-lived. Republicans took back the majority that fall.

Walker became the first governor in U.S. history to survive a recall challenge. Kleefisch became the first lieutenant governor to face one, as well as the first to survive one.

Act 10 saved taxpayers money. How was it also political?

Reining in the political power of unions was part of the plan behind Act 10, as Scott Fitzgerald, who was the majority leader of the state Senate, made clear at the time.

“If we win this battle, and the money is not there under the auspices of the unions, certainly what you’re going to find is President (Barack) Obama is going to have a much more difficult time getting elected and winning the state of Wisconsin,” Fitzgerald, who was elected to Congress last year, told Fox News in 2011.

What does Walker think about Frost's ruling?

While no longer in office, Walker responded to Frost's decision on X, calling it "brazen political activism."

"This makes the April 2025 Wisconsin Supreme Court race that much more important. We want a state where legislators and the governor make the laws, not the courts?" Walker said.

"Collective bargaining is not a right. It is an expensive entitlement," Walker said in a second tweet.

What happens to Act 10 next?

Assembly Speaker Robin Vos (R-Rochester) agreed with Walker and promised an appeal.

“This lawsuit came more than a decade after Act 10 became law and after many courts rejected the same meritless legal challenges," Vos said. "Act 10 has saved Wisconsin taxpayers more than $16 billion. We look forward to presenting our arguments on appeal.”

(This story was updated to add new information.)

Jessica Van Egeren is a reporter and assistant breaking news editor with the Milwaukee Journal Sentinel. She can be reached at jvanegeren@gannett.com.