How would you feel if you invited your coworker to a potluck and he or she showed up without a dish, ate a lot of food, and then took a plate home?

Corey Rosenlee, president of the Hawaii State Teachers Association, recently posed this scenario to Hawaii teachers, explaining what could happen if the U.S. Supreme Court decides in favor of an Illinois child support specialist name Mark Janus in his case against the American Federation of State, County and Municipal Employees (AFSCME).

In Janus, the Supreme Court will decide whether the law can compel all public-sector employees — including non-union members — to pay a mandatory “fair share” fee to the union that represents them to cover the union’s costs for negotiating contracts for all government employees.

Janus and conservative, corporate-backed organizations funding his case argue that requiring all public employees to pay their fair share violates their right to free speech. But this is a ruse.

The Supreme Court in an earlier case, Abood vs. Detroit Board of Education, protected freedom of expression for public employees by ruling that unions may assess fair share fees, but they are prohibited from using these fees to support political activities, including campaign donations.

Corporate-backed special interests want Abood overturned and have poured millions of dollars into aggressive public campaigns to weaken and destroy unions precisely because they are powerful advocates for working men and women.

In states like Wisconsin and Iowa, these conservative interests have expended considerable resources to pass so-called “right to work” laws that eviscerate the rights of private sector workers to effectively unionize and collectively bargain for better wages and benefits.

These same people and organizations are now directing their considerable resources to undermine, cripple and even eliminate public sector unions, thereby harming members of our communities who work as teachers, nurses, firefighters, police officers and other critical jobs.

This campaign almost succeeded two years ago when the Supreme Court heard the case, Friedrichs v. California Teachers Association, in which several California public school teachers sued the California Teachers Association claiming that the mandatory “fair share” fee violated their First Amendment rights.

At the time, I argued that weakening unions will weaken the middle class. Before the Supreme Court reached a decision, Justice Antonin Scalia passed away, and the Supreme Court rendered a deadlocked 4-to-4 decision.

With a vacancy to fill, Senate conservatives blocked Merrick Garland’s nomination to the Supreme Court to hold the seat open for a justice who would complete the job of overturning Abood. Conservative groups spent millions of dollars to aggressively support Neil Gorsuch’s nomination to replace Scalia on the bench.

The now nine-member Supreme Court, with Justice Gorsuch in place, is poised to use the Janus case — which closely mirrors Friedrichs — to finally overturn Abood.

If the Court rules in favor of Janus, many employees represented by public unions are expected to opt out of paying their fair share fees. This will drastically reduce the resources and power unions have to negotiate better wages, benefits and working conditions for all public employees — whether they pay their fair share fees or not.

A ruling against public unions will disproportionately impact women, especially women of color. According to the National Women’s Law Center’s analysis of census data, women make up a 56 percent majority of union-represented public sector workers. Women public-sector workers who are represented by unions also make on average 15 percent more than non-union members, or $6,500 more annually.

Clearly, women, public employees, and public unions would all lose if Abood is overturned. When unions are weak, income inequality rises. When unions are strong, working families can prosper. I know this first hand. My family entered the middle class after my mom joined in successfully unionizing her workplace.

With Justice Gorsuch now in place, unions and the country are likely to suffer a setback in this case. But the fight must continue.

Mazie Hirono is a U.S. senator representing Hawaii.