A trial is underway in North Dakota in a lawsuit against Greenpeace over its support for protests of the Dakota Access Pipeline. Filed by Texas-based Energy Transfer, the lawsuit alleges Greenpeace in 2016 engaged in or supported unlawful behavior by protesters of the pipeline,

The case is tied to protests in 2016 and 2017 of the Dakota Access Pipeline and its controversial Missouri River crossing upstream of the Standing Rock Sioux Tribe’s reservation. The tribe has long opposed the pipeline as a risk to its water supply. The pipeline was completed in 2017.

Dallas-based pipeline company Energy Transfer LP’s $300 million trial against Greenpeace USA is set to begin Monday in North Dakota. Energy Transfer is accusing the longtime nonprofit and other activists of defamation and damages over claims related to protests surrounding the construction of the nearly 1,