In a per curiam opinion [opinion, PDF] Monday, an equally divided US Supreme Court [official website] affirmed the judgment of the US Court of Appeals for the Ninth Circuit [official website] in Washington v. United States [docket].

The court was to determine whether road culverts that reduce fish habitat in Washington state violate a Native American fishing treaty, but said that the appeals decision would stand because the court was divided at 4-4, with Justice Kennedy abstaining.

The appeals court had determined [opinion, PDF] that in building and maintaining barrier culverts within what was known as the Case Area—large swaths of land, watersheds, and offshore waters adjacent to those areas—Washington violated, and was continuing to violate, its obligation to the tribes under treaties that required enough fish supplied to them.