The Federal Trade Commission (FTC) and a group of eight states have announced a proposed settlement with big ad agencies that will prevent them from working together to avoid certain platforms like X based on their political viewpoints.

In a complaint, the FTC argues that ad agencies violated antitrust rules by agreeing to a common set of brand safety rules, which would disfavor sites and services deemed to contain content like misinformation. That includes establishing groups like the World Federation of Advertisers’ now-defunct Global Alliance for Responsible Media (GARM) to coordinate collective brand safety efforts.

The FTC also alleges that organizations like NewsGuard, the Global Disinformation Index (GDI), Check My Ads, and Media Matters for America classified “disfavored opinions as ‘misinformation’” and lobbied ad buyers to “demonetize sites that hosted or shared such content.” Media Matters was also sued by X for reporting that it had found ads for major brands alongside pro-Nazi content.

If a federal judge approves the order, the ad agencies WPP, Publicis, and Dentsu will be prevented from making agreements with other ad agencies that would limit buying ads on any publisher “with respect to its news and political or social commentary content,” must file annual compliance reports for five years after the order is finalized, and must appoint a compliance monitor who will serve for five years.

”Dentsu remains fully committed to operating transparently, with integrity, and in strict compliance with all applicable laws,” Dentsu spokesperson Jeremy Miller says in a statement. “Our dedication to delivering value and maintaining the highest standards of compliance is unchanged.” A WPP spokesperson declined to provide an attributed statement to The Verge.

A GDI spokesperson pointed The Verge to a Financial Times opinion article published in January by co-founder and CEO Clare Melford. “A fully informed transaction between buyers and sellers is a key tenet of the free market. Far from coercion or censorship, GDI is simply one member of a community that seeks to make the internet a safer place for businesses and citizens alike,” Melford said.

(Melford’s US visa was denied late last year, with Secretary of State Marco Rubio saying that the presence of Melford and four others in the “the Global Censorship-Industrial Complex” would have “potentially serious adverse foreign policy consequences for the United States.”)

”This is supposed to be a collusion case, but we don’t work with the ad agencies signing the consent order and our ratings are based on non-partisan journalistic standards, not political orientation,” NewsGuard co-CEO Gordon Crovitz says in a statement.

World Federation of Advertisers’ Will Gilroy declined to comment. Publicis hasn’t replied to a request for comment.

“This unlawful collusion not only damaged our marketplace, but also distorted the marketplace of ideas by discriminating against speech and ideas that fell below the unlawfully agreed-upon floor,” FTC Chair Andrew Ferguson says in a statement. “The proposed order remedies the dangers inherent to collusive practices and restores competition to the digital news ecosystem.”

Last year, the FTC approved a merger between two other big advertising companies, Omnicom and IPG, if it included a similar ban on steering ad buys based on “political or ideological viewpoints.”