A North Dakota judge on Friday finalized a $345m judgment against Greenpeace in a lawsuit pursued by pipeline company Energy Transfer (ET.N) over the environmental group’s role in protests against the construction of the Dakota Access Pipeline.

The final judgment by judge James Gion was in line with a decision he issued in October, in which he slashed by almost half a damages award of about $667m that a jury had awarded Energy Transfer in March.

Greenpeace in a statement said it would seek a new trial and, if necessary, appeal the decision to the North Dakota supreme court, calling the lawsuit “a blatant attempt to silence free speech”.

“Speaking out against corporations that cause environmental harm should never be deemed unlawful,” Marco Simons, interim general counsel at Greenpeace USA and Greenpeace Fund, said in a statement.

Energy Transfer in a statement called the decision an “important step in this legal process of holding Greenpeace accountable for its unlawful and damaging actions against us during the construction of the Dakota Access Pipeline”.

It added it was “analyzing possible next steps that we may choose to take to make sure they are held fully accountable”.

The Dakota Access project near the Standing Rock Indian Reservation began in 2016 and was completed in 2017.

Construction of the pipeline, which now transports roughly 40% of the oil produced in North Dakota’s Bakken region, was met with fierce protests by environmental and tribal advocacy groups who said it would poison the local water supply and exacerbate the climate crisis.

Texas-based Energy Transfer first sued Greenpeace in a federal court in North Dakota in 2017, accusing it of spreading falsehoods about the project and paying protesters to disrupt construction.

The North Dakota jury delivered its verdict in March, including damages for defamation, trespassing and conspiracy.

Greenpeace countersued Energy Transfer in the Netherlands in February under a European law aimed at curbing lawsuits filed to harass or silence activists. That litigation is ongoing.