A pivotal trial over the embattled Dakota Access Pipeline opens today that could have grave consequences for protests in the US and the future of the environmental group Greenpeace.

Members of the Standing Rock Sioux and more than 500 other tribes protested the development of the pipeline alongside demonstrators who joined from across the US nearly a decade ago. Legal battles are still in motion, even after oil started flowing through the pipeline that runs from North Dakota to Illinois in 2017.

The company that operates Dakota Access, Energy Transfers, is suing Greenpeace for $300 million in a lawsuit that goes on trial this week. Energy Transfers claims that Greenpeace supported protesters’ “unlawful acts of trespass” and property destruction to stop construction. It also alleges that the organization spread false information about the company and concerns about the pipeline’s impact on the environment and cultural sites to the public and to banks financing the project.

Paying that amount in damages would be equivalent to about 10 times Greenpeace USA’s annual budget, according to organization. “If we lose, Greenpeace USA could face financial ruin, ending over 50 years of environmental activism,” its website says.

The green group says it’s become the target of one of the largest SLAPP suits on the books, referencing
Strategic Lawsuits Against Public Participation meant to deter civic action. Grassroots activists from Standing Rock say the suit is a threat to free speech across the board, and that the spotlight on Greenpeace misrepresents a movement that was led by Indigenous protesters rather than any outside environmental organization.

”Freedom of speech is on the line,” says Waniya Locke, a member of Standing Rock Grassroots. “This directly impacts everybody, not just Standing Rock, not just Greenpeace.”

Greenpeace has racked up support from more than 400 different organizations and some celebrities including Billie Eilish, Jane Fonda, and Susan Sarandon who recently signed an open letter to Energy Transfer. The letter says that the suit is trying to hold Greenpeace accountable for actions taken by unaffiliated individuals and “attempts to rewrite the history of the Indigenous-led opposition movement at Standing Rock – by absurdly alleging that Greenpeace orchestrated the entire resistance.” The case could have a chilling effect on peaceful protest, the letter warns.

“Our lawsuit against Greenpeace is about them not following the law. It is not about free speech as they are trying to claim. We support the rights of all Americans to express their opinions and lawfully protest,” Energy Transfer spokesperson Jeff Tieszen said in an email to The Verge.

Considering the company made more than $82 billion in revenue last year and is seeking an amount in damages that would be devastating for Greenpeace but not as significant for the company, “My instinct here is that this is a SLAPP suit,” Josh Galperin, associate law professor at Pace University, tells NPR. “Their real concern is the persistence of the protest – the way it is capable of turning public opinion.”

A federal court dismissed a similar suit Energy Transfer filed against Greenpeace in 2017. North Dakota, however, is one of only 15 states without anti-SLAPP laws. “The facts don’t change,” says Greenpeace USA national campaigns director Rolf Skar. “They’re asking for money that we don’t have, that they don’t need, for a pipeline that is already operating and making them money when they filed their initial lawsuit. So this is about silencing us.” The trial is scheduled to end on March 27th.