BISMARCK, N.D. (AP) — A federal judge has ordered another review of whether the already-operating Dakota Access pipeline might unfairly affect the Standing Rock Sioux.

It’s uncertain how the process will unfold, but there are two main possibilities. Federal officials who permitted the project to move North Dakota oil to Illinois could revise their analysis, or they could conduct a full environmental study.

The tribe says it will fight in court if there isn’t a full study. Texas-based pipeline developer Energy Transfer Partners expects a “limited” process with federal officials reaffirming prior conclusions.

The big question is whether the pipeline will be shut down while the case plays out. U.S. District Judge James Boasberg isn’t likely to decide until the fall, after lawyers on both sides have had a chance to make their arguments.