The federal district court decision of Judge Schreier that denied the plaintiff’s motion for a preliminary injunction in the case of Fox Drywall and Plastering, Inc. v. Sioux Falls Construction was a ringing endorsement of the Flandreau Santee Sioux Tribal Court of Appeals decision in this case. It is one of the few (and perhaps only) federal court decisions indicating that the tribal court’s subject matter jurisdiction over non-Indians in the Montana context was so certain that the plaintiffs were not entitled to injunctive relief in that they could not show the likelihood of prevailing on the merits. Judge Schreier also noted that “there is a significant public interest in recognizing a tribe’s sovereign right to regulate activities by non-members on tribal trust land and a tribal court’s right to enforce those regulations, as long as that regulation falls within the confines of Montana” (p. 33).
Here is the tribal appellate decision at issue: Flandreau COA Decision II
And the rest of the materials in the case are here.
Turtle Talk 
Common sense has prevailed; Montana has been applied fairly and correctly. If you engage is commercial business in Indian Country you should expect to be subject to the Jurisdiction of the Tribal Court. Especially where you are building a Casino on trust land; the economic heart of the Tribal government. We all know gaming revenue pays for many essential government services. FSST is providing employment for hundreds of Non-Indians at Royal River Casino; a legal remedy for breach of contract is very important.