A Wave of Amicus Briefs Piles Pressure on the U.S. Supreme Court to Untangle the National Sports Betting Patchwork

An international coalition of gaming regulators, the National Football League, and a massive bipartisan group of 39 states are urgently pressing the U.S. Supreme Court to intervene in New Jersey’s high-stakes legal battle against prediction market platform Kalshi. The petitioners argue that sharply divided federal appeals courts have created an untenable regulatory patchwork, leaving the legality of sports event contracts entirely dependent on the geographical location of the bettor.

The mounting pressure comes as a flurry of amicus briefs floods the Supreme Court docket ahead of Kalshi’s formal response in the case, Flaherty v. KalshiEX. The legal showdown centers on a fundamental regulatory question: whether federal commodities law shields sports-themed event contracts traded on exchanges registered with the Commodity Futures Trading Commission (CFTC) from traditional state-level gambling and gaming laws.

Regulators, States, and the NFL Line Up Behind New Jersey

The legal offensive against Kalshi’s product model has brought together an unusual alignment of sports leagues, state attorneys general, and international gaming watchdogs. On October 2, the International Association of Gaming Regulators (IAGR), which represents regulators worldwide, joined forces with the North American Gaming Regulators Association (NAGRA) to file a joint amicus brief. Just days later, Ohio led a coalition of 38 other states and the District of Columbia in submitting a separate brief on October 7. The NFL followed suit on October 8 with its own filing, backed by prominent legal counsel, including former U.S. Attorney General William Barr.

The core grievance uniting these diverse entities is the deep fracture in how federal appellate courts have treated Kalshi’s sports contracts. In April, the Third Circuit ruled in favor of Kalshi in the New Jersey dispute. Conversely, the Ninth and Sixth Circuits have ruled firmly against the platform, creating a glaring contradiction in federal jurisprudence.

"The same product, offered by the same company under the same federal registration, is presently shielded from state regulatory authority within the Third Circuit and subject to it within the Sixth and Ninth," the regulatory bodies wrote in their joint filing. NAGRA, whose membership includes various tribal authorities and Canadian provincial gaming regulators, leaned heavily on a September Ninth Circuit ruling concerning California tribes. Their brief summarized the issue bluntly: "Kalshi may reshuffle the cards, but it cannot change the hand: Its sports event contracts are class III gaming."

The state-level coalition, spearheaded by Ohio, pulled no punches in describing the current judicial landscape. Their brief characterizes federal and state courts as "hopelessly confused and divided," asserting that prediction markets "cannot strip the states of their core sovereign power through relabeling and window-dressing." Alongside Ohio, the brief was signed by major states such as Alabama, California, Michigan, Nevada, New York, and Pennsylvania, though notable heavyweights Texas and Florida declined to join. The states’ filing also highlights the broader regulatory friction by noting that nine of the signing states are currently involved in legal battles where the CFTC has attempted to block state enforcement actions.

Economic Stakes and Regulatory Gaps Highlighted by the NFL

The NFL’s intervention brings massive economic scale and immediate consumer protection concerns to the Supreme Court’s doorstep. According to the league’s amicus brief, a staggering $1.8 billion of the $3.3 billion traded across prediction markets on the opening Sunday of the professional football season was directly tied to NFL games.

The professional football league argued that both the CFTC and exchange operators like Kalshi have consistently ignored its requests to prohibit wagers that are "easily manipulable by a single person." Furthermore, the league expressed alarm over age restrictions, pointing out that prediction markets permit 18-year-olds to trade contracts on games, bypassing the stricter age limits universally required by regulated sportsbooks. The NFL has urged the high court to step in "before another NFL season goes by."

Despite the heavy momentum building against Kalshi at the Supreme Court, the legal battlefield remains fiercely contested across multiple jurisdictions. Demonstrating the ongoing uncertainty in the lower courts, a federal judge in Chicago granted Kalshi a partial win in its ongoing dispute with the state of Illinois on October 2, the exact same day international regulators filed their Supreme Court brief.

Legislative Intent and Lobbying Footprints

Adding another layer of complexity to the litigation, the case hinges in part on legislative history and the recorded statements of a former lawmaker who is now compensated by Kalshi. New Jersey’s petition to the Supreme Court highlights remarks made on the Senate floor in 2010 by then-Senator Blanche Lincoln of Arkansas. The Third Circuit dissent explicitly quoted Lincoln’s prophetic warning from that era, where she cautioned that "it would be quite easy to construct an ‘event contract’ around sporting events such as the Super Bowl," and noted that such contracts "would be used solely for gambling."

Public federal lobbying disclosures indicate that the Lincoln Policy Group, which lists Lincoln as a registered lobbyist, has reported collecting $480,000 in lobbying income from Kalshi since 2024. Additionally, Lincoln joined a roster of other former lawmakers in filing a supportive amicus brief on behalf of Kalshi during the earlier proceedings in the Third Circuit.

As legal observers monitor the docket ahead of Kalshi’s scheduled response due on November 9, prediction markets themselves are reflecting skepticism regarding the timeline of Supreme Court intervention. On Polymarket, market probabilities indicated just a 3% chance that the high court would formally accept a sports event contract case by October 31, and a 28% chance by the end of December, though trading volume on the year-end contract remained modest at approximately $24,000. Meanwhile, Kalshi’s broader Supreme Court strategy continues to look toward a heavily anticipated, pending rewrite of gaming rules by the CFTC.