The US Supreme Court heard arguments this week in Janus v. AFSCME, and most observers believe the justices are prepared to strike down agency fees for government employees—that is, the mandatory dues that public-sector workers pay to the unions that represent them. The implications of this decision could be staggering: Recent research suggests that “right-to-work laws” (which prevent agency fees from being imposed on all workers) dramatically reduce Democratic vote share, shift policy to the right, and reduce working-class representation in legislatures.

If the Court does indeed rule that these fees are unconstitutional, it will be on the grounds that the payments are “compelled speech,” as the plaintiffs argued. But while the conservative justices may be sympathetic to the free-speech claims of workers and and union beneficiaries who don’t want to pay union dues, they seems far less interested in other forms of coerced speech in the workplace.

The Court’s conservative majority has already placed stark limits on the speech rights of public-sector workers. In Garcetti v. Ceballos, the five conservative justices found that a deputy district attorney who faced retaliation for writing an internal memo detailing false claims in a search warrant did not have free-speech rights, because of his position as a government worker.

In a 1990 case, Rutan v. Republican Party of Illinois, liberals on the Court held that the First Amendment barred public-sector officials from making decisions about hiring or firing based on party affiliation. But in his dissent Justice Antonin Scalia argued that “Private citizens perhaps cannot be prevented from wearing long hair, but policemen can,” and thus, in his view, free expression by public-sector workers can be curtailed.

Justice Anthony Kennedy, who appeared to favor the plaintiff’s arguments on Monday, signed on Scalia’s dissent in Rutan. It is very difficult to find a logical thread here, but it is easy to find a partisan one—conservative jurisprudence may only be interested in protecting those free-speech rights when unions would be harmed.

In addition to happily limiting the free-speech rights of public-sector employees, the Supreme Court has also never been particularly concerned with the free-speech rights of private-sector employees, despite evidence that employers sometimes push workers to engage in political speech they may not want to.

In a new book called Politics at Work, political scientist Alex Hertel-Fernandez explores another form of coerced speech: in which employers prod workers to engage in political speech that benefits their company. Hertel-Fernandez documented the ways in which corporate managers can tell workers to attend protests, write to members of Congress, and even donate to company political-action campaigns. During the final leg of the 2012 campaign, when Mitt Romney visited an Ohio coal mine, the mine owners told workers that attendance was mandatory (and that workers would not be compensated). Workers told local reporters that “they showed up to the rally out of fear of losing their jobs or being disciplined in some other way.” One woman said that she felt her husband’s boss was “pushing the Republican choice on him and he felt intimidated.” To add insult to injury, the workers were forced to give up the day’s pay. The owner of the mine, Murray Energy, is among the largest corporate donors to the Republican Party. Robert Murray, the CEO, has pressured employees to contribute to Republicans and his company internally tracks who does and does not donate. Journalist Alec MacGillis documented that individuals who don’t donate to Republican candidates risk being demoted or even fired.

Koch Industries sends all employees pro-Republican mailers, and employees who post liberal items on social media risk firing or demotion. The Koch brothers also tightly manage whether employees can run for local office, and one employee said he was afraid to express his support for Obama by wearing a pin to work.

These are not isolated incidents. The CEO of Westgate Resorts sent a company-wide e-mail warning that voting for Obama could cost workers their jobs. Delta Airlines gives anti-union employees free flights to lobby members of Congress, even at risk of disrupting travel for paying customers.

Hertel-Fernandez offered evidence that in some workplaces employees feel strong pressure to toe the company line: He finds that in firms that more closely monitor workers, employees were more likely to engage in political activities at the behest of their employees. Employers also sometimes use warnings of job losses to prompt participation, and employees were most likely to engage in political speech at the behest of their employer in areas with high levels of unemployment. This coerced speech has a powerful effect on policy. Hertel-Fernandez found that managers who mobilize workers to engage believe that strategy to be as effective as other traditional strategies for changing public policy.

Other research has found that employees are far more likely to donate to candidates supported by the CEO of their company than other candidates.

In fact, one reason employers can coerce speech is because of the Citizens United decision, which Kennedy has often claimed was about free speech. As Hertel-Fernandez explained, the decision “permits managers to use their employees’ time and effort—a corporate resource—in elections.” Hertel-Fernandez wrote that “many employers can now require that their workers participate in partisan electoral politics, and can even discipline or even dismiss workers who refuse to engage in those activities.”

And while the Koch brothers deliver materials to workers telling them whom to vote for, unions are barred from distributing such materials. The Court’s priorities are clear: speech for corporations, but no speech for workers.

Janus is another test of our institutions: namely, how far conservatives on the Supreme Court are willing to go in order to reinterpret the law in order to achieve political goals. In Bush v. Gore, Republicans on the Court gifted the presidency to George W. Bush. In Shelby County, conservatives on the court helped Republicans with their black-voter-suppression agenda, thereby helping Republicans win an election because of the decline in black turnout.

Though liberals cheered on the NFIB decision, in which Roberts upheld the ACA, the majority ineptly rewrote the Medicaid expansion, a key GOP priority. Recent research suggests that allowing Republican governors to reject the Medicaid expansion was enough to swing the 2016 election to Trump. Citizens United mostly succeeded in improving the Republican Party’s chances in the 2010 midterms, and has further increased their state-level power since.

Now Republicans are asking the court to crush their political opponents once again. The GOP has been pretty explicit that destroying public-sector employee unions is a purely political project.

Tim Phillips, president of Americans for Prosperity, the centerpiece Koch advocacy group, said “public employee unions, which have only gotten stronger, have only gotten better-funded, have only gotten better organized,” and the AFP has therefore dedicated millions to crushing them. Grover Norquist has said that if the right’s war on unions is successful, “the modern modern Democratic Party will cease to be a competitive power in American politics.”

At the state level, this project has been carrying on for years. Hertel-Fernandez explored American Legislative Exchange Council bills that were passed between 1996 and 2016 to reduce the power of unions. These laws were generally designed to do two things: first, to make it more difficult for public-sector unions to raise money, and second, to make it more difficult for unions to spend the money on politics. These laws have their intended effect: The passage of an conservative bill targeting unions reduces both public-sector-union density and revenues, according to Hertel-Fernandez’s research. He found that the passage of an ALEC bill reduces public-sector-union density by about 5 percentage points.

The impact on union revenues is similarly large. But the impacts go beyond simply reducing union revenues: The passage of these bills dampens the political mobilization of public-sector workers.

In Wisconsin, Scott Walker passed a law to limit collective bargaining—but he didn’t do it in a uniform manner. Much like Republicans did in Iowa, Walker limited collective bargaining only for unions that represent more Democratic-leaning constituencies (teachers), while exempting Republican constituencies (police officers). Six years after Walker’s measure passed, the state’s largest teacher union lost more than half of its members and its budget fell from around $17 million in 2012 to $9 million in 2014.

The mainstream media often do a poor job contextualizing just how extreme, and political, the Roberts Court has been. Alito, Thomas, Gorsuch and Roberts are just like Scalia before them: dedicated ideologues working to achieve the political aims aims of the Republican Party, which has been trying to crush the political power of Democratic-leaning unions for decades. Janus might deliver a death blow.