BRITISH AIRWAYS, American Airlines and Iberia have had their request for anti-trust immunity approved by the US Department of Transport.
The decision paves the way for the airlines to collude legally on transatlantic fares and services.
The deal puts BA on a level playing field with European rival carriers Lufthansa and Air France, who both form part of antitrust-based alliances.
Virgin Atlantic, which has long been a vocal opponent of the tie up, said the US DoT's decision to approve anti-trust immunity was bad news for consumers.
However, BA's chief executive, Willie Walsh, said: "This final approval is fantastic news for all three airlines and the Oneworld alliance." As a result of the deal, both BA and AA will have to relinquish slots at Heathrow.