Casino operator MGM Resorts is bankrolling a Connecticut tribe’s fight against the state government’s authorization of a third tribal casino.

Monday saw the Schaghticoke Tribal Nation file a federal lawsuit based on its claim that the Special Act 15-7 the state government approved last year is unconstitutional. The Act authorized a joint venture of the operators of the state’s two tribal casinos – Mohegan Sun and Foxwoods Resort Casino – to build a commercial casino off tribal lands near the Massachusetts border.

MGM filed a lawsuit against the Act last August, arguing that the company had not been allowed to apply to operate this third casino. The state sought a dismissal of MGM’s suit based on the state AG’s belief that MGM has no standing to sue.

The Schaghticoke tribe got involved after it applied for its own commercial casino license, approval for which the tribe believed the state had granted but which the state subsequently denied, prompting a messy series of public clarifications.