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The Supreme Court hears arguments Monday in the case of Mark Janus, a child support specialist from Illinois, who is suing AFSCME because he has no interest in financially supporting the union’s political activities.

Since Janus is not a member of the union, he doesn’t pay the same amount in dues as union members. But thanks to a Supreme Court decision in 1977, he is forced to pay the union “agency fees,” feeding the coffers of an organization he wants nothing to do with.

The high court will determine whether these agency fees are unconstitutional. Since freedom of association is a basic tenet of the American idea, it would be stunning if the Supreme Court rules to uphold the 1977 precedent. Considering a similar case deadlocked 4-4 after the death of Justice Antonin Scalia, the presence of Justice Neil Gorsuch gives advocates of worker freedom great hope that agency fees will soon be a relic of the past.

To say this is a big case would be an understatement. More than 5 million government workers in 22 states are currently forced to pay these unholy tithes to big government unions just to keep their jobs. That enormous spigot of cash gives unions like AFSCME tremendous political power. But what would happen if public employees are actually given a choice?

According to the unions, if Janus wins, government functions will be completely crippled and public unions will be destroyed. “The politicians who want to slash public services and crush unions are busting budgets with extravagant tax breaks,” wrote AFSCME President Lee Saunders in a recent op-ed.

Observers of the Janus case can look to Wisconsin to find out what really happens when government employees have a choice. To put it mildly, Saunders is wrong.

In 2011, Gov. Scott Walker and Republicans in the Legislature pushed through a bold reform called Act 10. Among other taxpayer-friendly reforms, the landmark law allowed public employees to opt out of their unions without risking their job, prohibited government from withholding union dues from paychecks, and required annual re-certification of all government unions.

Union bosses and agitators threw a massive temper tantrum, and Saunders told a union mob that he had a “score to settle” with Walker. Unions predicted the sky would fall as a result of Walker’s reforms. Government operations would grind to a halt, schools would close their doors, and chaos would seize the state, they breathlessly exclaimed.

Seven years later, none of those predictions has come to pass. In fact, Wisconsin is stronger than ever.

Contrary to frantic claims that education in Wisconsin would be devastated, Wisconsin now boasts the second-highest high school graduation rate in the country, and the number of advanced placement exams taken by high school students has increased 47 percent since 2010. Students’ test scores have held steady, and all Wisconsin students are now taking the ACT.

Once-bloated government unions have shrunk now that people can elect not to join, aren’t forced to pay, and have an opportunity to vote on whether to have a union in the first place. The biggest example is the Wisconsin Education Association Council (WEAC). Before the passage of Act 10, the state’s largest teachers union had almost 100,000 members. As of 2015, the union stood at just 36,074 active members.

WEAC also suffered the largest revenue decline among all state teachers’ unions in 2014-15. During just that time, the union’s revenue dropped more than $3 million.

Symbolizing its sharp decline as a political powerhouse propped up by coercive dues money, the union even put its lavish 51,000-square-foot headquarters up for sale in 2016.

The most recent data show overall union membership in Wisconsin has declined from 354,882 members in 2010 to 218,233 in 2016, a drop of 38.5 percent, according to a MacIver report. As it turns out, giving workers the freedom to leave a union results in steep declines in union membership as unwilling members vote with their feet.

While union membership is now confined to those workers who actually want to be in a union, the number of state and local government workers in Wisconsin has increased by 10,000 between 2013 and 2016, according to the Census Bureau. So claims by people like Saunders that letting workers opt out of a union will decimate public services simply aren’t true.

Not only were the sky-is-falling claims wrong, but Wisconsin is in impressive fiscal health. The state’s budget surplus now stands at $385 million, $137 million more than projected. Walker and the conservative Legislature have been able to cut taxes by $8 billion over the last seven years. This is all possible while maintaining good public services and giving public employees the freedom to not join a union.

The Wisconsin experience shows us that worker freedom means smaller, less powerful unions. It also shows us that government will continue to function and students will continue to learn and thrive.

No one wants to have their paychecks plundered to fund a union they want nothing to do with. Everyone should be given the basic freedom of association guaranteed by the Constitution. Everyone should be free to choose the political activity their money goes to. If Mark Janus slays the AFSCME giant in the Supreme Court, the big government union bubble will deflate just as it did in Wisconsin.

Most important, millions of public workers will have their basic human rights restored.