Rather than roll the dice in a hazy regulatory environment, the gaming industry is pressing the U.S. Treasury Department for greater clarity about how casinos should handle money connected to the booming legalized cannabis market.

In a letter to federal regulators this week, the American Gaming Association said the friction between the federal ban on marijuana and the state legalization push “continues to present complexities and challenges for many types of financial institutions, including casinos.” The association, a top lobbyist for casinos, requested more information about how the Treasury Department’s guidance for grappling with legalized marijuana—first released in 2014—applied to the gaming industry.

That guidance document, issued by the department’s Financial Crimes Enforcement Network, spelled out how institutions should report transactions involving funds they know or suspect to be connected to the marijuana business.

FinCEN, as the Treasury network is widely known, said the “obligation to file a [suspicious activity report] is unaffected by any state law that legalizes marijuana-related activity.” But it acknowledged the U.S. Justice Department’s guidance for marijuana enforcement, known as the “Cole memo,” which took a hands-off approach to state-licensed cannabis businesses. Under Attorney General Jeff Sessions, the Justice Department is now reviewing marijuana policy.

The FinCEN guidance urges financial institutions to report transactions as “marijuana limited” if they involve a marijuana-related business that does not implicate the Cole memo—named after then-Deputy Attorney General James Cole—or violate state law. For transactions involving a marijuana-related business that is believed to be violating state law or implicating one of the Cole memo priorities, FinCEN suggests more serious terminology in suspicious activity reports: “marijuana priority.”

For the gaming industry, the guidance left unanswered the question of how casinos should handle high-rollers and other customers who are gambling with marijuana-connected money.

As the American Gaming Association wrote in its letter to regulators, “the guidance appears designed primarily for banks and other financial institutions that have corporate entity customers. Casino patrons, on the other hand, are individuals.”

“Accordingly, we seek clarification of the industry’s obligation in preparing [suspicious activity reports] for individuals who own or are employed by such state-licensed marijuana-related business,” wrote Geoff Freeman, president and CEO of the American Gaming Association. “Specifically, we need to know whether and how casinos should use the 2014 marijuana guidance for filing [suspicious activity reports] on patrons whose gaming funds appear or are known to be from marijuana-related businesses.”

The American Gaming Association, in addition to its in-house stable of lobbyists, has turned to Brownstein Hyatt Farber Schreck and other firms in recent years for work on issues including daily fantasy sports betting and enforcement of illegal gambling.

Marijuana-related money was just one of several issues the American Gaming Association addressed in the letter, which it sent as the Treasury Department conducts a sweeping review of regulations ordered by the Trump White House. The Treasury Department invited comments in a “request for information” that referenced Trump’s executive order directing agencies to convene regulatory reform task forces and an earlier order that called for two rules to be eliminated for every new regulation issued.

The casino industry’s attention to financial regulations around marijuana comes at a pivotal time. Last month, Nevada—home of the nation’s capital of casino gambling—became the fifth state with stores selling marijuana for recreational use. Under the state’s law, stores can sell up to an ounce of marijuana to customers age 21 and older. As The Associated Press reported in July, out-of-state tourists visiting Las Vegas and other Nevada destinations are expected to make nearly two of every three purchases.

California, the largest state to approve recreational marijuana and home to dozens of casinos, is crafting its own regulatory scheme that the state wants to have in place by Jan. 1. A working group pinpointed a number of banking and finance issues, among other areas of high priority. Many of those issues facing California, and other pot-legal states, were addressed recently at the first-ever Cannabis Law Institute in Denver.