This educational guide is based on the linked primary sources. It is not a Court publication, is not affiliated with the Court, and is not legal advice.
In brief
Overview
According to Petitioner (Mr. Cooley), according to Petitioner (Mr. Cooley), respondent (Joshua James Cooley) does not contest tribal sovereignty itself but asks that the Court respect the boundaries of tribal authority as previously defined by this Court.
Background and question before the Court
Late one night Officer James Saylor of the Crow Police Department observed Joshua James Cooley driving a truck on a public highway within the Crow Reservation, noted that Cooley appeared non‑native, had watery eyes, and had two semiautomatic rifles in the front seat.
What each side argues
Petitioner (Deputy Solicitor General Eric J. Feigin)
According to Petitioner (Deputy Solicitor General Eric J. Feigin), indian tribes, like other sovereigns, have the core inherent authority to investigate and detain suspects within their borders for the violation of another sovereign's law.
According to Petitioner (Deputy Solicitor General Eric J. Feigin), the holding lacks any meaningful support, substantially chills tribes' ability even to enforce their own laws against their own members, and endangers everyone on Indian reservations. It should be reversed.
According to Mr. FEIGIN, non‑Indians cannot be subject to tribal adjudication, which is another line of demarcation.
Respondent (Joshua James Cooley)
According to Petitioner (Mr. Cooley), cooley does not challenge tribal sovereignty; he simply asks that the Court respect the boundaries of tribal sovereignty as previously defined.
Amicus (Mr. Henkel)
According to Mr. HENKEL, indian tribes do not possess sovereign authority over non‑Indians, and Congress has plenary authority over Indian affairs.
According to Mr. Henkel, if conduct rises to an ongoing breach of the peace that endangers public safety, it fits under the Ninth Circuit’s standard for tribal authority.
According to Mr. Henkel, there is virtually no remedy for unlawful tribal seizure other than exclusion of the evidence; tribal officers enjoy sovereign immunity and cannot be sued under 42 U.S.C. §1983.
What happened at oral argument
Justice Gorsuch asked where the line is, noting that the Major Crimes Act precludes tribes from trying certain non‑native individuals for major crimes.
Justice Kavanaugh asked why the Court should not simply follow prior cases on the issue.
Justice Barrett asked whether the investigative authority extends past Terry stops into arrests, noting that arrests mark the beginning of the adjudicatory process.
Justice Kavanaugh also asked whether the line of authority comes from the Constitution.
What the Court decided
Why it matters
Terms to know
No glossary terms are available for this guide.
Primary sources
Read the source materials on the official site or open the immutable repository copy used for this guide.
- a94dd280af60d5c4630d-r1-566e0829d217ceeb.pdfopinion
- f3c3aa258260c8445f51-r1-0369eb1be177bacb.pdforal argument transcript
Guide generated September 27, 2026. Automated validation accepted this version.