When the U.S. Supreme Court heard oral arguments in February in a high-stakes case for public-sector labor unions, Justice Sonia Sotomayor wanted to talk about "labor peace."

Her line of questioning -- and comments made by others during the oral arguments -- may have seemed tangential to the case at the time. But in the months since, teacher strikes have shut down school systems and overwhelmed capitols in five states. Their protests have more often than not led to increased education funding and teacher pay, illustrating the power that unions can wield.

In the case, called Janus v. AFSCME, the central issue is whether government workers who don’t want to belong to the unions should have to pay unions for services the unions provide, such as contract negotiations or arbitration. The plaintiff in the case, an Illinois government employee backed by many conservative groups, says paying so-called fair-share fees to the unions violates workers’ free speech rights.

But there are exceptions to First Amendment protections, particularly when the government can show it has a “compelling interest” in regulating speech. For instance, public employees have fewer free speech rights than private employees if the government can argue that the restrictions are necessary to achieve its goals. That was the point Sotomayor was getting at.

“We permit the government to fire people -- deprive them of all money, not just a fair-share fee ... if they speak outside of the government’s approved policy messages or messages generally,” Sotomayor, who was appointed by President Barack Obama, told a lawyer who wants to get rid of the fair-share fees.

“So ... why can’t [the] interest in having workplace peace [and] routine, in which issues are decided in a collective way, why isn’t that a compelling interest comparable to the others?”

“The government purpose here,” she later added, “is labor relations and labor peace.”

David Franklin, Illinois’ solicitor general, echoed those concerns while defending the fair-share, or agency, fees.

“When unions are deprived of agency fees,” he said, “they tend to become more militant, more confrontational. They go out in search of short-term gains that they can bring back to their members and say, ‘Stick with us.’”

The comments didn't attract a lot of attention at the time, but they seem more salient in light of all the public-sector labor protests since.

The oral arguments happened in late February, while West Virginia teachers were striking and marching on the state Capitol for better pay and benefits. The West Virginia rallies inspired teachers in Oklahoma, Kentucky, Arizona, Colorado and North Carolina to try similar tactics.

All of the states that had major teacher protests this year, other than Colorado, are "right-to-work" states, meaning employers, including government agencies, can’t force employees to join a union or to pay fair-share fees.

“Most of these protests have been in states where teachers have little or no collective bargaining rights. Those that do have reasonably strong unions and collective bargaining rights generally have better terms and conditions of work, and a greater voice in such things,” notes Cynthia Estlund, a professor at New York University School of Law, who signed on to a friend-of-the-court brief in the Janus case. “That seems to me like it strengthens the conventional argument in favor of collective bargaining.”

Indeed, Illinois Attorney General Lisa Madigan says that one reason Illinois supports collective bargaining -- and the requirement for non-union members to pay fair-share fees -- is to avoid workplace conflicts.

“The state of Illinois, and, actually, any government, has a significant interest as an employer in having a group of organized employees to bargain with,” she says. “It’s much easier for us to deal with that when everyone is paying their fair share toward collective bargaining, toward contract administration, as well as toward grievances.”

Still, Illinois isn't immune to labor strikes.

In 2012, Chicago teachers staged a weeklong walkout, and last year, state workers represented by AFSCME, the union involved in the Supreme Court case, threatened to strike when contract negotiations with Gov. Bruce Rauner reached an impasse.  (Rauner has made limiting the power of public-sector unions a major focus of his and, in fact, his anti-union actions led to the lawsuit that is now before the high court.)

Even with the uptick in labor disruptions, the arguments about labor peace are unlikely to bolster Illinois’ case with the Supreme Court, says Steven Schwinn, a professor at the John Marshall Law School in Chicago.

First of all, the concept of labor peace can mean different things in different contexts. The kind of labor peace that could be relevant to the Janus case is about whether all employees pay for the benefits they receive under collective bargaining. Schwinn says that’s an “analytically distinct issue” from the striking teachers’ grievances in other states, where the focus is on pay, benefits and working conditions.

“Even if the five conservatives on the court took note of [the teacher strikes], they would think it would be a different problem,” Schwinn says.

More importantly, he says, the conservative majority on the high court seems certain to strike down the agency fees. In fact, this is the third time in the last five years that the court has heard a case that raises the issue. The first time, the case was decided on other grounds. The second time, the court split 4-4 after the death of Justice Antonin Scalia. But now it seems poised to finally do away with the fair-share fees.  

“The justices have made up [their] minds on this case,” Schwinn says. “The handwriting is on the wall. I don’t think anything is going [to] influence the conservatives on the court to take labor peace as a serious issue.”

That outcome could seriously weaken public employee unions' revenue and ability to wield influence. It would essentially establish a right-to-work policy for the entire country, at least when it comes to government employees.

Schwinn, however, doubts the ruling would have as big of an impact as state right-to-work laws because the court’s ruling would be narrower.

“The court would not be making policy toward public-sector unions in the ways that Wisconsin or Michigan did. Its ruling is likely to result in diminished power for the unions, but that is less than a legislature adopting broad, sweeping measures to hinder, hamper and beat up on public-sector unions in a variety of ways,” he says.

Schwinn also predicts that an anti-union ruling could incite more labor unrest, which is what Sotomayor had originally warned about during the oral arguments.

“There could be a backlash,” Schwinn says. “People can engage in collective action to protect their economic interest -- even without a union to organize them.”