The business practices of Visa will come under scrutiny in a Federal Court action bought by the Australian Competition and Consumer Commission over an esoteric foreign exchange service known as dynamic currency conversion.Dynamic currency conversion is a service that allows a card-holder with a Visa card issued outside Australia to make a purchase at a known exchange rate rather than having the exchange rate applied later.The ACCC said yesterday that it had commenced proceedings in the Federal Court against Visa Inc and related Visa entities over alleged contraventions of the Competition and Consumer Act.The ACCC alleged that Visa "misused its market power" by "deterring businesses from supplying DCC services in Australia and preventing businesses in Australia from supplying DCC services in competition with Visa's own currency conversion service."The regulator asserted in a media release that, from May 2010 to October 2010, Visa "implemented and maintained rules which prohibited the further expansion of the supply of DCC services on point of sale transactions on the Visa network by its rival suppliers of currency conversion services in many parts of the world, including in Australia."The ACCC said this "froze the pool of merchants who could offer DCC during the period in which the ban was in force."The regulator also alleged that "from at least October 2007 to date, Visa has banned the use of DCC on transactions at ATMs on Visa cards in Australia."The ACCC also alleges that Visa engaged in exclusive dealing by supplying access to its payment network to Australian banks and, in turn, retailers, on condition they didn't acquire DCC services from alternative DCC suppliers.  Alternative suppliers in the Australian market include Pure Commerce (owned by Euronet) and Travelex. Visa began lifting its moratorium on DCC service providers in most international markets from late 2010.In a statement issued from Singapore, Visa said that it "permits DCC at merchant point of sale."It acknowledged that it "does not permit the service at ATMs."Visa said it "will vigorously defend itself" against the ACCC's claims, but declined to field questions on the history of the matter.