Likewise, Travis P. Nelson, a partner of the New Jersey-based law firm Reed Smith's financial industry group, co-wrote in a briefing for his clients that the rescission of the Cole Memo is “anticipated to also result in the swift repeal of, or at least substantially call into question the continued effectiveness of, certain FinCEN guidance.”

U.S. Attorney General Jeff Sessions reportedly blindsided federal officials who advise financial institutions in states where cannabis is legal by revoking the 2014 Cole Memo on Jan. 4. The memo lowered the risks from federal prosecution for financial institutions as long as they did not violate the memo's top enforcement priorities such as keeping marijuana away from minors, making sure pot sales revenue was not being funneled to criminal enterprises, gangs or cartels, and preventing state-authorized marijuana activity from being used as a cover for trafficking other illegal drugs or money laundering.

Based on the Cole Memo's top enforcement priorities, FinCEN-issued guidance in 2014 that clarified dozens of red flags for financial institutions that would trigger priority suspicious activity reports, such as a marijuana business receiving substantially more revenues than its competitors, excessive cash deposits and withdrawals relative to local competitors or third parties with no connection to the accountholder making deposits.

If the guidance is revoked, the risk of legal liability increases significantly for executives and board members at about 100 credit unions and 300 banks that currently serve the pot industry, according to the latest FinCEN stats.

An influential conservative organization called for the prosecution of those who provide financing for marijuana operations.

In a position article, Charles Stimson, a senior legal fellow and manager of the National Security Law Program for the Heritage Foundation, called for FinCEN to revoke its guidance and oppose efforts to expand banking services to the marijuana industry. He also called for the prosecution of financial institutions.

“Federal anti-money laundering statutes make it illegal to engage in financial transactions designed to promote illegal activities, including drug trafficking,” he wrote. “Start with one major marijuana financier and successfully prosecute it.”

Former federal prosecutor Robert G. Marasco, a San Diego-based attorney and partner for the Dinsmore & Shohl law firm's litigation department, acknowledged it would be difficult to do business with anyone in the marijuana industry if FinCEN rescinds its guidance.

But he doesn't think federal authorities are going to stop California state laws that on Jan. 1 legalized the recreational use of cannabis. And he doesn't believe that it was simply coincidence that Sessions rescinded the Cole Memo on Jan. 4, just three days after California officially legalized recreational pot on Jan. 1.

“So when Sessions said, 'Hey, just want to remind everyone that we're still here, and you're still on our radar,' maybe even more so now, their view is bring it on,” Marasco said. “Because for them, there is such an incredible financial opportunity as they see it. For them, they don't think that the authorities are really ever going to put a stop to it. Even if [the feds] would [raid pot shops], they're going to end up in front of a jury of people who are OK with this kind of business.”

Even though California was the first state to pass medical marijuana laws in 1996, the Drug Enforcement Agency subsequently conducted raids of the legal medical cannabis establishments, and then later mailed letters reminding pot shop owners that medical marijuana was still illegal under federal law, according to local media reports. As a result, some medical marijuana businesses did shut down, according to local media reports. However, in 2015 a federal court in California ruled the DEA could no longer shut down medical pot dispensaries operating under state law.

For now, credit unions are taking the “business as usual” stance. But they are also monitoring for any new signals from FinCEN or for any heads up from their federal legislators about what may or may not happen in the coming days or weeks.

“There is not much use in speculating what could happen at this point, because revoking the FinCEN guidance completely is just one of many events we could see at the federal level,” Rachel Pross, chief risk officer for the $697 million Maps Credit Union in Salem, Ore., which has been serving marijuana businesses since 2014, said. “That is why we stay in very close contact with our government officials, regulators and legal counsel. Banking this industry really boils down to strategic risk management, and any exit from the industry would be extensively vetted and carefully deployed. We have had a written exit strategy in place from the outset of serving this industry. Our exit strategy includes specific triggers and subsequent action plans.”

A bipartisan group of more than 30 House members and a bipartisan group of about 18 senators have recently sent letters to Blanco urging him to preserve the FinCEN guidance to continue access to financial institutions for the marijuana businesses that are complying with state and local laws.

Credit unions are also keeping a close eye on the Rohrabacher-Blumenauer amendment, the only federal law that is preventing DEA raids on medical marijuana shops and other programs in 46 states that have legalized, to varying degrees, the production, distribution and possession of marijuana for medicinal purposes. While 29 states have legalized medical marijuana, an additional 17 states allow cannabidiol, an ingredient from the marijuana plant minus its intoxicating effects, to treat patients with serious medical conditions, according to the National Conference of State Legislatures. In nine states, Alaska, California, Colorado, Maine, Massachusetts, Nevada, Oregon, Washington, Vermont and Washington, D.C., recreational use of marijuana is legal. Kansas, Nebraska, South Dakota and Idaho are the only states that have no marijuana access laws, the NCSL reported.

The Rohrabacher-Blumenauer amendment, originally passed by Congress in 2014, was attached to the annual appropriations bill that forbids the Department of Justice from using federal funds to crack down on medical marijuana stores or patients. Sessions and his supporters have been lobbying to get rid of the amendment, according to national media reports.

After the House passed the continuing resolution for the appropriations bill to keep the government open on Jan. 22, the amendment was preserved but only until Feb. 8.

Representatives Dana Rohrabacher of California, Don Young of Alaska, Jared Polis of Colorado, and Earl Blumenauer of Oregon last February founded the Congressional Cannabis Caucus to serve as a forum for members of Congress to work together to establish a more rational approach to federal cannabis policy.

Last year, Congressman Rohrabacher proposed a long-term solution by introducing H.R. 975 that if enacted would allow residents and businesses to participate within the confines of a state's medicinal or recreational marijuana program without running afoul of federal law. Although H.R. 975 has more than 40 co-sponsors, it may be an uphill battle for this bill, or any bill, to win the votes needed in Congress to become law.