Washington (CNN) The US Supreme Court on Monday sided with a Wyoming Native American tribe, ruling that a 19th-century treaty between the tribe and the state did not expire when Wyoming became a state.

The court ruled in favor of Native American rights in an unusual split where conservative Justice Neil Gorsuch teamed up with the court's four liberals to form a 5-4 majority.

It's the latest case where a justice broke with his fellow conservatives . Last week, President Donald Trump's other appointee, Justice Brett Kavanaugh, sided with the liberals in a 5-4 case against Apple, holding that a group of iPhone owners could bring a lawsuit accusing Apple of violating US antitrust rules.

Cases such as Monday's treaty rights dispute often defy the usual ideological alignments. More consequential tests of Trump's two appointees and the depth of their conservatism are likely to come in June, the final month of the annual session, as the justices resolve disputes over, for example, partisan gerrymandering, federal regulatory power, and the separation of church and state.

In the majority opinion, Justice Sonia Sotomayor -- joined by Justices Ruth Bader Ginsburg, Stephen Breyer, Elena Kagan and Gorsuch -- wrote that an 1868 treaty between the Crow Tribe and the United States in which the tribe ceded most of its territory in modern-day Wyoming so its members would have a right to hunt on "unoccupied" parts of the land did not expire after Wyoming gained statehood.

Read More