In a recent ruling, a federal judge in Arizona has halted the state's attempt to bring criminal charges against Kalshi, a prediction market provider, at least for the time being. This decision comes in response to a motion filed by the Commodity Futures Trading Commission.

District Judge Michael Liburdi ruled that Arizona cannot proceed with an arraignment of Kalshi as scheduled, after the state announced plans to file 20 criminal charges against the company for allegedly violating Arizona law by offering betting products. The judge's ruling stated that the Commodity Futures Trading Commission has demonstrated a strong likelihood of succeeding in its claim that Arizona's gambling laws are preempted by federal law.

As a result, Arizona's pursuit of state action could potentially violate the Supremacy Clause. The temporary restraining order, which is in effect for two weeks, prohibits Arizona from enforcing its gambling laws in any criminal or civil enforcement actions related to contracts listed on Commodity Futures Trading Commission-regulated markets.

The Commodity Futures Trading Commission chairman, Michael Selig, welcomed the judge's decision, stating that Arizona's use of state criminal law against companies complying with federal law sets a dangerous precedent. The case is part of a broader dispute between the Commodity Futures Trading Commission and several states, including Arizona, over the regulation of prediction markets, also known as event contracts. While state courts have often sided with the states, federal courts have yielded mixed results, with some ruling in favor of the Commodity Futures Trading Commission's authority to oversee these markets.