Under Twitter’s new ad policy, environmental groups and fossil fuel companies alike won’t be allowed to run ads with “the primary goal of driving political, judicial, legislative, or regulatory outcomes.” The company will also place restrictions on ads aimed at educating or raising awareness on issues like climate change.

The new details on cause-based advertising were released today after Twitter’s initial announcement last month that it would end all political advertising on its platform. That decision raised alarm bells for environmental advocates who are concerned that the new ban would give an advantage to fossil fuel companies that could continue to promote their products and views unencumbered by the restrictions.

“We need accountability.”

“Twitter’s new ad policy will allow fossil fuel companies to buy ads defending themselves and spreading misleading info—but won’t allow organizations fighting the climate crisis to buy ads holding those companies accountable,” 2020 presidential candidate Sen. Elizabeth Warren tweeted on November 5th. “We need accountability.”

“Taking all this into consideration,” Twitter CEO Jack Dorsey tweeted in response.

After that backlash, Twitter announced that it will restrict rather than outright ban “cause-based advertising.” It is also providing more details about how advertising from advocacy groups and Big Oil and Gas will be scrutinized.

“Cause-based advertising can facilitate public conversation around important topics,” Twitter’s new policy states. “Advertising should not be used to drive political, judicial, legislative, or regulatory outcomes.”

Fossil fuel companies will still be allowed to purchase ads as long they avoid those topics, and any educational or awareness-raising ads from companies also need to be “tied to the organization’s publicly stated values, principles, and/or beliefs.”

Advertisers will need to go through a certification process to ensure they’re not breaking the new rules. But Twitter will also be relying on individual users to flag violations. “If we see companies that are trying to push messaging that is clearly meant to be inflammatory or meant to manipulate a conversation, that’s something that we look at as sort of a one-off basis as it’s escalated,” Del Harvey, Twitter’s VP of trust and safety, told reporters on a Friday call. “We are absolutely going to make mistakes here and we firmly believe that it is far better for us to start trying to get this right and then give people a way to tell us when we’re getting it wrong, than to try to wait until we have the full fruition for every potential way that people could try to game us.”

“We are absolutely going to make mistakes here.”

Environmental activist group Sunrise Movement — which is behind the push for a Green New Deal — hasn’t relied on Twitter’s paid reach, but it’s still concerned about the consequences of Twitter’s new rules.

“We’ll be watching closely to see how Twitter implements this policy. Fossil fuel companies like Exxon are not normal companies. Their business model is completely incompatible with what scientists say is necessary to stop climate catastrophe,” Sunrise Movement communications director Stephen O’Hanlon wrote to The Verge in an email. “When they advertise about the promise of fossil fuels, they aren’t just promoting their product — they are propagating the kind of pseudo science that got us in this mess in the first place.”

Twitter’s new advertising policies will be live on November 22nd, and more details about what enforcement will look like are expected to be announced closer to that date.

Makena Kelly contributed reporting for this story.