The Supreme Court hears arguments Monday in a pair of cases that members of Congress say could influence political discourse in the United States, warning that the justices either could stymie debates on controversial policies or bolster the influence of big-money anonymous donors.

The cases center on California’s requirement that nonprofits disclose a list of major donors of more than $5,000 to state regulators who seek to police charitable fraud. Nonprofits already must file that information with the Internal Revenue Service, which must keep it confidential.

Two charities with histories of backing conservative causes challenged the law as an unconstitutional burden on their freedom of association under the First Amendment because the risk that the state would disclose the information could expose donors to “potential intimidation, retaliation, and harassment,” and dry up the charities’ sources of support.

But the cases play out against the backdrop of a long and contentious debate about the influence of money in politics and shaping public discourse, so it has drawn the attention of lawmakers who have been the most outspoken on the issue.

The cases also touch on some of today’s hot-button issues, including the power of social media, the Jan. 6 attack on the Capitol by Trump supporters, and even how anonymous donors have tried to influence the confirmation process for Supreme Court justices.

A decision in the cases is expected before the end of the term at the end of June. The justices have a number of paths in the case, including simply sending it back to a lower court or focusing the ruling narrowly on just these two nonprofits.

Senate Minority Leader Mitch McConnell of Kentucky, who has played a leading role in legal challenges to campaign finance laws, filed a brief in the cases to tell the justices that “donor disclosure requirements threaten great practical harm — harassment, boycotts, violence—to those who espouse controversial or unpopular views.”

Supporters of the two charities in this case, Americans for Prosperity Foundation and Thomas More Law Center, faced those dangers, but donors also face “economic reprisals and social ostracism” only made worse by the advent of the internet, McConnell’s brief states.

“That is especially true in an era where a few providers so dominate the flow of information online,” McConnell’s brief states. “Just to take one of innumerable examples, YouTube is able to significantly restrict the flow of information coming out of United States Senate hearings — it takes no imagination to see that powerful media companies could silence, ostracize, or otherwise threaten anyone revealed to contribute to the ‘wrong’ causes.”

That refers to YouTube’s removal of a video of Senate testimony by a physician on a possible treatment for COVID-19. McConnell’s brief was filed by Don McGahn, a White House counsel under former President Donald Trump.

But a group of Democratic senators told the justices in a brief that the challenges to the California law are “the latest move in a steady and methodical campaign pursued by powerful interests to both cement and obscure their influence over the public sphere” since the Supreme Court’s decision in Citizens United v. Federal Election Commission.

That 5-4 decision in 2010 found that the First Amendment’s free speech rights meant the government could not limit corporations from spending money on elections.

The Democrats say that exploded political spending “by deep-pocketed interests,” and they urge the justices to avoid a ruling in these cases that will more broadly undo disclosure laws, since the Citizens United decision in part depended on transparency of donors to safeguard political integrity.

“The bigger prize being sought is blanket constitutional protection of dark money and secret influence,” the Democratic senators’ brief states.

The brief was filed by Sens. Sheldon Whitehouse of Rhode Island, Patrick J. Leahy of Vermont, Ron Wyden and Jeff Merkley of Oregon, Richard J. Durbin and Tammy Duckworth of Illinois, Amy Klobuchar of Minnesota, Chris Coons of Delaware, Richard Blumenthal of Connecticut, Tammy Baldwin of Wisconsin, Mazie K. Hirono of Hawaii, Elizabeth Warren and Edward J. Markey of  Massachusetts, Cory Booker of New Jersey, and Chris Van Hollen of Maryland.

In a separate brief, Maryland Democratic Rep. John Sarbanes, who sponsored legislation that includes provisions to strengthen requirements to disclose campaign-related expenditures and donors, noted that some groups such as the U.S. Chamber of Commerce had brought up election-related disclosure in these cases about a California state law.

Sarbanes urged the justices “to take care to cast no doubt” on their previous rulings that upheld disclosure requirements related to elections.

As far as dangers of transparency go, the Democratic senators told the justices that “dark money helped sponsor a rally that prompted a violent insurrection at our Capitol,” and that they place their trust in law enforcement to address whatever threats individuals may face as a result of their public stances.

“If it is good enough for politicians who are far more visible and vulnerable, it should be good enough for the extraordinarily wealthy dark-money influencers dominating our public sphere from the shadows,” the Democratic senators wrote.

Separately, Whitehouse, Blumenthal and Rep. Hank Johnson of Georgia wrote to Justice Amy Coney Barrett and asked her to recuse herself from the case, pointing out that Americans for Prosperity Foundation “is the nonprofit arm of the billionaire industrialist Koch family’s Americans for Prosperity, which spent heavily on a campaign to install Barrett on the Court.”