The case is In re Harper (Malloy v. Wilserv CU). The CA10 held that tribal law gaps forced the court to resort to Oklahoma law, which appears to have undermined the purpose of having tribal law in the first place. It’s a bankruptcy case, with commercial law as a backdrop.
Here are the materials:
Appendix and Record (incl. two bkrcty ct opinions, CA10 BAP opinion, and background docs)
Wilserv Credit Union Opening Brief
Wilserv Credit Union Reply Brief
– Attachment (incl. letter from State of Okla to tribal members)