The ACLU and environmental activists celebrated Thursday after reaching a settlement agreement with South Dakota's Republican Gov. Kristi Noem and state Attorney General Jason Ravnesborg to end what critics called "their unconstitutional attempts to silence pipeline protestors."

"We will celebrate this win but remain vigilant against further government attempts to outlaw our right to peacefully assemble."

—Dallas Goldtooth, IEN

The settlement is a result of a lawsuit filed by the national ACLU, the group's state chapter, and the Robins Kaplan law firm challenging provisions from various state laws, including South Dakota's "Riot Boosting" Act, which threatened activists with up to 25 years in prison. It follows a federal court ruling last month that temporarily blocked enforcement of the provisions.

"The state's anti-protest efforts were plainly unconstitutional," Stephen Pevar, senior staff attorney with the ACLU's Racial Justice Program, said in a statement Thursday.

"This settlement helps ensure that no one has to fear the government coming after them for exercising their First Amendment right to protest," he said. "This settlement should also serve as a lesson for other legislatures considering similar anti-protest efforts."

BREAKING: In response to our lawsuit, South Dakota's governor and attorney general today backed down from their unconstitutional attempts to silence protesters of the Keystone XL pipeline. Let this be a lesson to other states: If you criminalize protest, we will sue. — ACLU (@ACLU) October 24, 2019

The contested provisions of South Dakota's laws are part of a trend of recently enacted, highly controversial legislation in a number of Republican-controlled states to criminalize protests, particularly those targeting "critical infrastructure" such as fossil fuel pipelines.

As ACLU staff attorney Vera Eidelman explained in a blog post Thursday:

In the last few years, we have witnessed a legislative trend of states seeking to criminalize protest, deter political participation, and curtail freedom of association. These bills appear to be a direct reaction from politicians and corporations to some of the most effective tactics of those speaking out today, including water protectors challenging pipeline construction, Black Lives Matter, and those calling for boycotts of Israel. These legislative moves are aimed at suppressing dissent and undercutting marginalized and over-policed groups voicing concerns that disrupt current power dynamics.

In South Dakota specifically, several environmental and Indigenous groups—including those involved in the lawsuit that led to the settlement—have spent years protesting the long-delayed Keystone XL pipeline.

Brendan Johnson, a partner with the Robins Kaplan law firm, said Thursday that "by equating peaceful organization and support of protest with 'riot boosting' and incitement to riot, the government stifled our clients' abilities to speak out against the Keystone XL pipeline."

"By equating peaceful organization and support of protest with 'riot boosting' and incitement to riot, the government stifled our clients' abilities to speak out against the Keystone XL pipeline."

—Brendan Johnson, attorney

Johnson's firm and the ACLU represented the Sierra Club, Dakota Rural Action, the Indigenous Environmental Network (IEN), and NDN Collective, as well as two individuals from those groups.

"South Dakota knew these laws couldn't stand up to our legal challenge so rather than face embarrassment they decided to capitulate," one of the individual plaintiffs, IEN's Dallas Goldtooth, said of the settlement, which still needs final approval from a federal court.

"We will celebrate this win," Goldtooth added, "but remain vigilant against further government attempts to outlaw our right to peacefully assemble."

The other individual plaintiff, Nick Tilsen of NDN Collective, called the state's Riot Boosting Act "an insult to the Constitution and an attempt to muzzle the voices of the people and our movement to defend Mother Earth."

"This settlement accomplishes everything that we set out do with the lawsuit and makes the temporary injunction a permanent one," said Tilsen. "Onward, we will continue to fight for air, land, water, and our rights."

Pre-construction activities are already underway for the Keystone XL pipeline, which when completed would carry up to 830,000 barrels of crude oil daily from the Alberta tar sands, across Montana and South Dakota, to Nebraska.