https://lawandcrime.com/supreme-court/scotus-just-heard-arguments-in-a-case-about-what-happens-when-tribal-police-arrest-a-non-native-american-person-what-to-knowThis involves what authority tribal police have to arrest non-tribe members. Gorsuch actually seems to be siding with the defendant based on his questioning and against the tribe in fact, although based more on Fourth Amendment grounds. Might have an interesting decision breakdown, seeing as how both Clarence Thomas and Sonia Sotomayor seemed to be the most sympathetic to the government's case.
Based on the questioning so far, Gorsuch and ACB seem like pretty likely bets to side with the defendant, Sotomayor and Thomas to side with the government, Breyer leaning toward the government, Alito and Kavanaugh unclear, and no mention of any questions from Kagen or Roberts.