State officials asked a federal court Monday to dismiss the Schaghticoke Tribal Nation’s challenge of the 2015 law that enabled the Mashantucket Pequot and Mohegan tribes to begin a process that could lead to their opening a third Connecticut casino on nontribal land.

The Kent-based Schaghticokes claim the law violates the equal protection clauses of the U.S. and Connecticut constitutions and should be declared unconstitutional. They filed a lawsuit March 7 in U.S. District Court in Hartford, naming Secretary of the State Denise Merrill and Jonathan Harris, commissioner of the state Department of Consumer Protection, as defendants.

MGM Resorts International, the gaming operator that's building a $950 million resort casino in Springfield, Mass., is helping finance the Schaghticokes’ suit, which is similar to one MGM filed last August.

The state’s motion to dismiss the MGM suit is pending.

Both suits take aim at Special Act 15-7, which spelled out the process the Mashantuckets and the Mohegans, respective owners of Foxwoods Resort Casino and Mohegan Sun, must follow in jointly pursuing a third Connecticut casino to compete against MGM’s Springfield facility. The law allowed the tribes to form a “tribal business entity” to seek site proposals from Hartford-area municipalities willing to host a casino.

Ultimately, no third casino could open unless the legislature passes a law expressly permitting it. The casino-owning tribes are expected to push for passage of such a law next year, by which time their partnership is to have chosen a site for the proposed third casino. Sites in Hartford, East Hartford and Windsor Locks are being considered.

Assistant Attorney General Robert Deichert, who submitted the motion to dismiss the Schaghticokes’ suit, writes that Special Act 15-7 “does not injure” the Schaghticokes and that the tribe, as a result, “lacks standing to challenge it.”

Richard Velky, chief of the Schaghticokes, criticized the state’s motion in a statement Monday night.

“Today's motion to dismiss is just the latest instance in a long history of the state’s denial of fairness and justice to the Schaghticoke Tribal Nation,” he said. “Rather than address STN’s complaint on the merits, the state raises a series of procedural technicalities, all of which lack merit. The idea that a state-recognized tribe lacks standing to challenge a law that specifically excludes it in favor of two other named tribes is contrary to fundamental principles of fairness, equal protection and the right of everyone to have their day in court. We look forward to ours."

Former U.S. Sen. Joseph Lieberman of Connecticut, an attorney with the New York firm of Kasowitz, Benson, Torres and Friedman, is representing the Schaghticokes.

In the state's motion, Deichert says that Special Act 15-7 does not preclude other entities from pursuing commercial casino development in Connecticut.

In fact, the Schaghticokes, long recognized as a tribe by the state but not by the federal government, indicated in their suit that they were “ready, willing and able to develop a new and innovative commercial casino.” They said they had completed a market analysis showing that a commercial casino in western or southern Connecticut “would be feasible and profitable.”

State officials dispute the Schaghticokes’ claims.

“As noted above, STN (Schaghticoke Tribal Nation) does not — and cannot credibly — allege that it has operated a casino, or allege that there is any certainty that STN will be in a position to do so in the relatively near future,” Deichert writes. “The best STN can muster is allegations that if this Court rules in its favor, it plans to pursue unspecified ‘opportunities’ with unidentified partners who may or may not exist and are unlikely to exist given the challenging gaming market STN acknowledges.”

The Mashantuckets and the Mohegans revealed last week that they had drafted proposed changes in their revenue-sharing agreements with the state in the event their partnership succeeds in developing a third casino. Tribal officials said they had run the proposed changes by the U.S. Bureau of Indian Affairs, which said it believes the tribes could jointly own a third Connecticut casino without jeopardizing agreements that require them to pay the state 25 percent of their casinos’ slot-machine winnings.

An MGM official said last week that the tribes were “overstating” the significance of the BIA’s feedback.

b.hallenbeck@theday.com