The Obama administration on Friday issued guidelines that potentially open banks to marijuana businesses.

Banks are now free to provide services to marijuana-related businesses in states like Colorado and Washington, where sales of the drug are permitted. Regulators stressed that the move will enable financial intuitions to better report possible criminal activity.

The Treasury Department will require that banks file reports on marijuana businesses “to satisfy regulatory obligations in this area.” The Financial Crimes Enforcement Network, a division of the Treasury, said the information will give law enforcement greater insight into marijuana business activity.

“Our guidance provides financial institutions with clarity on what they must do if they are going to provide financial services to marijuana businesses and what reporting will assist law enforcement,” said Jennifer Shasky Calvery, director of FinCEN.

Although 20 states and the District of Columbia have legalized marijuana to some degree, the drug is illegal under federal law. Banks have so far avoided doing business with marijuana enterprises, seeking clarification on the issue.

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