California Treasurer Fiona Ma pleaded with federal lawmakers Wednesday to enact safe harbor legislation aimed at encouraging more banks and credit unions to accept state-licensed marijuana businesses as customers.

Ma, testifying before the U.S. House subcommittee on consumer protection and financial institutions, noted that California has explored creating its own public bank and authorizing a closed-loop banking system as alternatives to the cash-dominated cannabis market that exists today.

None of those proposals are preferable, Ma said, to federal legislation that would shield existing depositories from prosecution under money laundering laws.