The Indian Gaming Association, tribal gambling groups, and 23 Native American tribes have urged an Illinois federal judge to toss cryptocurrency exchange Coinbase's suit against the state as it tries to prohibit the company from offering event contracts to consumers as a form of sports betting.

The IGA, the National Congress of American Indians, the Indian gambling associations of five states, tribal regulators, and the 23 federally recognized tribes submitted a proposed amici brief on Friday supporting state Attorney General Kwame Raoul and the members of the Illinois Gaming Board.

The proposed friend of the court brief said Coinbase Financial Markets Inc. wrongly seeks to prevent Illinois from applying the state's gambling laws to federally regulated transactions that are subject to federal law under the exclusive jurisdiction of the Commodity Futures Trading Commission.

"Coinbase comes before this court and asks it to wholly abandon the national policy of state and tribal sports-betting regulation and to turn decades of federal law on its head. The court should not be persuaded to do so," the tribes and tribal groups argued.

Congress passed the Indian Gaming Regulatory Act in 1988 to promote tribal economic development and self-sufficiency, according to the brief. Not only do tribes have primary jurisdiction over their lands, but like states, tribes also have a sovereign interest in determining what gambling activities may take place on those lands, the brief claimed.

"America's history is replete with prospectors taking resources from Indian lands without permission from tribes," the brief said. "But Congress put a stop to that practice long ago. Yet Coinbase would have this court believe that, without so much as a whisper of legislative intent, Congress gave it permission to enter Indian lands and siphon gaming revenues away from tribes over such tribes' objections. Congress did no such thing."

Coinbase's incorrect reading of the Commodity Exchange Act seeks a reversal of congressional policy and Supreme Court precedent that would lead to the evisceration of existing tribal-state gambling compacts, according to the proposed amicus brief.

The Illinois federal court as of Tuesday afternoon had not yet ruled on whether to grant the tribal groups' motion for leave to file the proposed amicus brief.

Illinois, Connecticut, and Michigan were all sued by Coinbase on Dec. 18 over their attempts to regulate the trading platform's prediction market offerings. The company argued that the states are illegally trying to apply their gambling laws to federally regulated transactions that fall under the jurisdiction of the Commodity Futures Trading Commission.

Coinbase alleges that the states are trying to prohibit the company from offering to consumers event contracts, which the suits say are "a type of derivative instrument extensively regulated by federal law that can be traded only on federally registered exchanges in transactions facilitated by federally registered intermediaries."

According to the complaints, Coinbase would begin offering event contracts in January to consumers in Illinois, Connecticut, Michigan, and throughout the U.S. The contracts allow individuals to make predictions about future events, such as sports games or political elections.

In a separate yet similar case in Tennessee federal court, U.S. District Judge Aleta A. Trauger recently denied a bid to file an amicus brief by tribal groups including the Indian Gaming Association, the National Congress of American Indians, as well as the Indian gambling associations of four states and 21 federally recognized tribes.

Judge Trauger in her one-page order on Jan. 27 denied without explanation the Jan. 23 bid to file the friend of the court brief as prediction market Kalshi also sues state gambling regulators over the company's sports wagers. Kalshi sued the Tennessee Sports Wagering Council on Jan. 9 after receiving a cease-and-desist letter from the council threatening the company with criminal and civil penalties for its allegedly illegal sports event contracts.

Meanwhile, in Connecticut, legal battles by Coinbase and Kalshi over the legality of sports-related event contracts also led to proposed amicus briefs by the IGA, NCAI, and other tribal entities. The briefs agree with the state that the federal Commodity Exchange Act does not preempt state gambling laws and say that the act also does not abolish the Indian Gaming Regulatory Act.

On Friday, U.S. District Judge Vernon D. Oliver of Connecticut granted the tribal amici leave to file their brief.

Counsel for the amici, Coinbase, and Illinois did not immediately respond Tuesday to requests for comment.

The tribal groups and tribes are represented by Joseph H. Webster, Elizabeth A. Bower, Jens W. Camp, and Alexandra K. Holden of Hobbs Straus Dean & Walker LLP, Bryan Newland of Powers Pyles Sutter & Verville PC, Yuhaaviatam of San Manuel Nation and San Manuel Gaming and Hospitality Authority counsel Michael Hoenig, and Scott Crowell of Crowell Law Office Tribal Advocacy Group PLLC.

Coinbase is represented by George D. Sax of Scharf Banks Marmor LLC, and Benjamin R. Walker, Yaira Dubin, Akash M. Toprani, Jeffrey B. Wall, James M. McDonald, and Rishabh Bhandari of Sullivan & Cromwell LLP.

Illinois is represented by Darren Bernens Kinkead and R. Douglas Rees of the Illinois Attorney General's Office.

The Illinois case is Coinbase Financial Markets Inc. v. Raoul in his official capacity as Attorney General for the State of Illinois et al., case number 1:25-cv-15406, in the U.S. District Court for the Northern District of Illinois.

The other cases are Coinbase Financial Markets Inc. v. Tong et al., case number 3:25-cv-02121, in the U.S. District Court for the District of Connecticut, and Coinbase Financial Markets Inc. v. Dana Nessel in her official capacity as Attorney General of Michigan et al., case number 2:25-cv-14092, in the U.S. District Court for the Eastern District of Michigan.