With the conservative-dominated Supreme Court set to hear a case that poses the "biggest threat to organized labor in years" next week, members of National Nurses United (NNU)—the largest organization of registered nurses in the U.S.—rallied across the country on Thursday to highlight the crucial role of unions in protecting workers from corporate exploitation.

"We need to defend the trade union movement, we need to grow the trade union movement."

—Sen. Bernie Sanders (I-Vt.)

"It's the union that brings many safety laws in legislation and public regulatory protections. It's the union dues that fund those efforts," said Maureen Dugan, RN, who works at the University of California San Francisco. "It's the nurses in my hospital, in my region, in my whole state that make up the strength of our union and our ability to protect our patients, our license, and our profession."

"Americans should be worried about #Janus Supreme Court case" and its threat to #unions says RN Liz Downard, pointing out Calif is ONLY state in U.S. with safe nurse-to-patient staffing ratios bc @CalNurses fought for and won that legislation. "Hospitals just care about $." pic.twitter.com/LAhCsnwHtC — California Nurses (@CalNurses) February 22, 2018

The case under consideration—Janus v. AFSCME Council 31—could determine whether public sector unions are allowed to collect what are called "fair share" fees from workers to cover the costs of collective bargaining.

As the Huffington Post's Dave Jamieson notes, "Although fair share fees have been upheld as legal for decades, the high court's conservative majority is likely to strike them down as unconstitutional."

"If the court rules against AFSCME, the entire U.S. public sector would essentially be a 'right-to-work' zone―meaning employees could no longer be required to pay anything to the unions that bargain on their behalf," Jamieson adds.

Speaking at an NNU rally in Chicago on Thursday, Sen. Bernie Sanders (I-Vt.) said "there is a war going on against the working class in America" and argued unions are "the last line of defense."

"We need to defend the trade union movement, we need to grow the trade union movement," Sanders declared. "And every person in America, whether you're in a union or not, has got to understand that the reason [the rich] are attacking the trade union movement is they know the trade unionists are the last line of defense against this reactionary, corporate agenda, which wants to give more to the rich and take away from the middle class and working families."

Watch:

Hear @SenSanders' message at @NationalNurse’s rally against #Janus in Chicago today: We’ve got to stand together and make sure everyone knows that unions protect not only their members but everyone who works for a living! #1u pic.twitter.com/MwkEp6xs1L — NationalNursesUnited (@NationalNurses) February 22, 2018

Thank you @SenSanders for standing in solidarity with @NationalNurses nurses at our rally against #Janus in Chicago today! Nurses need union support to ensure profits for the rich and powerful do not come at the expense of public health and safety! #1u pic.twitter.com/Na2aCIXUN0 — NationalNursesUnited (@NationalNurses) February 22, 2018

According to a report published by the Economic Policy Institute (EPI) earlier this week, the Janus case did not arise out of widespread worker opposition to "fair share" fees.

"Rather, the fair share cases are being financed by a small group of foundations with ties to the largest and most powerful corporate lobbies," the report notes, highlighting the large role played by groups like the right-wing Liberty Justice Center, which is supported the Charles Koch Institute and similar pro-corporate organizations.

"This case is one of the most important cases to corporate interest groups. It is one of the cases that made Senate Republicans so determined to block President Obama's nominee to the Supreme Court," EPI labor counsel Celine McNicholas, who co-authored the report, concluded in a statement. "The outcome of Janus will affect millions of working people across the country and will impact the public services we depend on these workers to provide."