Some political groups may no longer be able to hide the identities of their donors after the full Supreme Court on Tuesday reversed a decision by Chief Justice John G. Roberts that had stopped a lower court ruling requiring the disclosures.

The full court, which has eight members at the moment, denied an application for a stay — or delay — of the lower court ruling in a case involving the conservative group Crossroads Grassroots Policy Strategies, which has been fighting since 2012 a lawsuit demanding that it disclose its donors.

The case involving Crossroads, and on the other side the liberal-leaning group Citizens for Responsibility and Ethics in Washington, dates back to 2012 when CREW filed a complaint with the Federal Election Commission alleging that the conservative group had violated federal campaign finance laws by failing to disclose the names of donors who funded campaign ads.

Then on Aug. 3 of this year, U.S. District Court Judge Beryl Howell essentially sided with CREW and gave the commission 45 days to come up with new regulations that would require more disclosure of donors to groups like Crossroads.

“This is an important decision which will help insure that voters have valuable information they need in evaluating advertising which is unquestionably aimed at trying to influence how they vote in elections,” campaign finance law professor Rick Hasen wrote on his Election Law Blog. “It does not solve all of the current disclosure problems, but this is a victory for transparency.”

FEC commissioner Ellen Weintraub, a Democrat, called the decision in a tweet “a real victory for transparency. As a result, the American people will be better informed about who’s paying for the ads they’re seeing this election season.”

The lower court’s decision, which the Supreme Court is no longer blocking, requires the disclosure of donors who contribute more than $200 to organizations’ “independent expenditure” efforts aimed at influencing federal elections. Independent is supposed to mean that the groups act without coordination with a candidate’s official campaign.

Crossroads filed an emergency application to the Supreme Court on Friday asking for a stay pending appeal, arguing that the lower court’s decision “mere weeks before the impending election, invalidates and will shortly vacate a foundational Federal Election Commission … regulation promulgated without controversy over 38 years ago.”

Crossroads added in its Friday filing that 501(c)(4) nonprofit organizations, like Crossroads GPS, “are not political committees but engage in limited activities that address matters of public concern near elections.” The decision could result in “chilling core First Amendment speech and association,” the filing added.

Crossroads, and other groups like it from both sides of the political aisle, routinely run TV and radio ads aimed at influencing elections or public policy debates. But they do not routinely disclose their donors, in what have come to be called “dark money” groups.

A recent report called “Dark Money Illuminated” by the nonpartisan campaign finance overhaul group Issue One ranked Crossroads GPS as its No. 2 biggest dark money spender since the Supreme Court’s landmark 2010 Citizens United v. FEC decision, which paved the way for super PACs and other avenues of political money outside of candidates and political party committees.

Crossroads GPS, according to Issue One’s report, disclosed to the FEC spending $110 million on political ads.

A lawyer for Crossroads, former FEC chairman Michael Toner of the firm Wiley Rein, declined to comment on the case after his side’s Friday filing and did not immediately respond to a request for comment after the Supreme Court’s move on Tuesday.

“This is a great day for transparency and democracy,” CREW Executive Director Noah Bookbinder said. “Three courts, including the Supreme Court, have now rejected Crossroads’ arguments for a stay, meaning we’re about to know a lot more about who is funding our elections.”