Tesoro High Plains Pipeline Co. is urging the Eighth Circuit to reject an appeal from members of the Three Affiliated Tribes seeking to intervene in its lawsuit over federal trespassing claims. Tesoro argues the U.S. government adequately represents the landowners' interests and that their involvement would complicate the case. The dispute centers on a 500-mile pipeline crossing Fort Berthold Reservation lands without a valid right-of-way. The federal government does not oppose their intervention.