Cliff Owen/AP - Sen. Charles Grassley (R-Iowa) on Capitol Hill in April.
Sen. Charles Grassley (R-Iowa) on Capitol Hill in April. (Cliff Owen/AP)

Two prominent senators have raised concerns about recent guidance from the Treasury Department that explains how banks can provide services to marijuana-related businesses without running into trouble with federal authorities.

The department’s Financial Crimes Enforcement Network, known as FinCEN, released guidelines in February saying banks must confirm that their pot-selling clients are licensed and registered with their states and ensure that their activities would not violate state laws or trigger enforcement actions by the Justice Department, among other recommendations.

MORE: Administration clears banks to accept funds from legal marijuana dealers

Sens. Chuck Grassley (R-Iowa) and Dianne Feinstein (D-Calif.) issued a letter to FinCEN Director Jennifer Calvery on Tuesday challenging the agency’s authority to “offer regulatory guidance on illegal activity.” They said the move “turns FinCEN’s mission on its head.”

The lawmakers, who head the Senate Caucus on International Narcotics Control, asked FinCEN to answer a series of questions about the basis and implications of its guidance.

“Congress and the president may reconsider marijuana’s legality, but until federal law is changed, selling marijuana, laundering marijuana proceeds, and aiding and abetting those activities all remain illegal,” the letter said.

(Matthew Staver/Bloomberg)

Twenty states and the District of Columbia allow marijuana-related activity to one degree or another, with Colorado and Washington state legalizing the drug while other jurisdictions allow it for medicinal purposes.

The Justice Department announced last summer that it would not challenge state laws that have legalized production, sale, possession and recreational use of marijuana.

Deputy Attorney General James Cole issued a memo in February saying marijuana was still illegal under federal law, but that the department would focus its enforcement efforts on limited priorities such as preventing sales from benefiting criminal groups such as gangs and cartels and thwarting attempts to transport the drug between states where it is legal and illegal.

Grassley contends that the Justice Department “put the financial system in a quandry” by saying that “the Justice Department would essentially ignore federal law in Washington and Colorado,” according to a statement from his office on Friday.

Grassley’s office also said that FinCEN’s guidance could make the agency a “partner in helping facilitate the dirty money coming into the financial system.”

FinCEN’s guidance said that banks must file “suspicious activity reports” on every marijuana-related business they serve, essentially flagging all of the establishments for federal authorities. Each organization must be classified in one of three ways:

“Marijuana limited” filings: Applies to pot-related businesses that do not appear to have violated state laws or engaged in activities that would trigger Justice Department action.

“Marijuana priority” filings: Applies to pot-related businesses suspected of activities that could trigger DOJ action or violate state laws.

“Marijuana termination” filings: For the businesses with which banks have decided to cut ties to avoid possible money laundering.

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