The Biden administration has opened an inquiry into whether a casino revenue sharing deal between the Seneca Nation of Indians and New York State is legal, a potentially significant step for the tribe that has been ordered by an arbitration panel and federal judges to pay $500 million in missed casino payments to Albany.

The Senecas filed a motion last week with the U.S. District Court in Buffalo to halt enforcement of a judgment that the tribe should make the payments that have accumulated since the Senecas halted annual casino revenue sharing with the state in 2016.

The court request by the Senecas comes after two key letters were written by federal officials last week raising questions about whether the state should be able to continue getting casino revenue sharing payments from the Senecas.