FARGO, N.D. (AP) — A federal judge on Wednesday ordered the U.S. Army Corps of Engineers to conduct a full environmental review of the Dakota Access oil pipeline, nearly three years after it began carrying oil.

U.S. District Judge James Boasberg wrote that the easement approval for the pipeline remains “highly controversial” under federal environmental law, and a more extensive review is necessary than the environmental assessment that was done.

The judge asked both sides to file briefs on whether the pipeline should continue to operate while the review is carried out.