Thanks to a rule first drafted in 2011, debit card issuers must give merchants the opportunity to choose between at least two unaffiliated networks when routing transactions.

However, at the time the market did not have the systems in place to support multiple networks for card-not-present transactions.

While the technology has evolved to address this, some issuers are still not supporting more than one network, an issue that has become more pronounced with the growth of online payments.

Says the Fed: "The final rule will encourage competition between networks and incentivise them to improve their fraud-prevention capabilities."

Fed Governor Michelle Bowman issued a dissenting statement over questions about how the rule will affect community banks with respect to fraud and the cost of compliance.