Just to provide some background knowledge for you guys.

As said before tribal police can only arrest tribal members. Tribal police can detain non-tribal members on tribal land, they simply just wait for a city, state or county agency to come arrest the non-tribal member.

However a year or two ago a law was passed saying that if a tribal officer has gone through the same training and background testing as a regular non-tribal officer is required to go through then that tribal officer can seek a county comission from the county sheriff (basically deputizing the tribal officer) if the tribal officer is granted a county comission he has the authority to arrest all people, doesn't matter if they are tribal or not. This issue was not well liked by county sheriffs and to my knowledge the only tribal police department that has officers who have county comissions are the Tulalips which have Snohomish county sheriff authority.

The only reason that tribes want their officers to have county comission is because of the casino industry. The Snoqualmie tribe for example was building a tribal police department so they could police the Snoqualmie Casino, while they were building the police department the tribe basically paid the king county sheriffs department for police services. Well the person who was hired as the police chief of the Snoqualmie tribe went to the sheriffs office asking that his officers be county commissioned so they could enforce all laws just like a county deputy. Well he soon learned that the King County Sheriffs office does not commission any agency no matter if its a state, tribal or federal agency. Since then the Snoqualmie tribe PD is basically gone and they are still paying the county for police services.