First and foremost, always carry a valid Montana fishing license, obey all local and federal regulations and stay below the high water mark at all times.
A tribal officer has the right to approach you and ascertain who you are (i.e., tribal member or not). Beyond that, if you are not a tribal member and you are below the high water mark, the tribal officer has no jurisdiction, and may not confiscate your personal property or issue you a citation. On the Bighorn River, if you are recreating below the high water mark, you do not need to hold or possess a tribal permit.
If you are confronted by a tribal officer and you are not a tribal member, state you are not a tribal member and show him identification. If asked if you have a tribal permit, indicate you are not a tribal member and not required to hold a tribal permit. If you wish, you may show your Montana license. If you are issued a citation, accept the citation if it is offered, and do not post any money or relinquish any property. Under no circumstances should an angler breach the peace. Don't voluntarily turn over or relinquish any property, but if the tribal officer actually gets close enough to grab equipment do not resist in any way. If anything is taken from you, request a detailed receipt signed by the officer with his badge number or other identifier. If you are with an angling partner and have a camera - take pictures and document where the officer approached you and what transpires during the encounter. After an encounter, write down all the details you can remember as soon as you can to preserve a record.
And please, if you are lawfully recreating on the Bighorn River below the high water mark and are confronted by a tribal officer, please report the incident to Region 5, Montana Fish, Wildlife and Parks, Billings, MT (406) 247-2940.
Special thanks to Region 5 Montana Fish, Wildlife and Parks for their assistance with this matter, as well as our good attorney friends!