It will be up to banks to decide whether to allow the use of credit cards to buy recreational marijuana.
Dozens of stores are offering patrons payment alternatives to cash, but they require a bank account.
According to The Denver Post, Visa has said their previous policy was to ensure that no illegal transactions enter their systems.
That position has softened lately, with Visa on Monday saying it's putting the burden on merchant banks to decide the definition of illegal.
Federal regulators have said that banks can't process payments for illegal drugs without risking prosecution. That warning has made it difficult for some marijuana businesses to accept credit cards, though many still accept credit cards through pre-existing banking relationships.