A lawsuit in Washington state and another case before the U.S. Supreme Court are part of a coordinated campaign that experts say is pushing once-fringe legal theories to the nation’s highest court and represents the most serious challenge to tribal sovereignty in over 50 years.

Maverick Gaming, which operates 19 card rooms in Washington and casinos in Nevada and Colorado, is challenging a 2020 law that allows sports betting only on tribal lands. The lawsuit, filed in federal court in Washington state, claims the law created a “discriminatory tribal gaming monopoly.”

But it goes further, arguing gaming compacts between Washington state and tribes are based on race and therefore discriminate unconstitutionally against people who run non-tribal casinos.