Airlines said that unless an immediate solution was found they would be plunged into a legal limbo, banned by Europe’s data protection laws from handing the details to the US and banned from landing in the US unless they have handed over the data.

The European Court of Justice judgment caused outrage among anti-terrorism policymakers on both sides of the Atlantic, prompting claims that it is fuelled by anti-Americanism and shows that Europe is soft on terrorism. However, it was hailed as a triumph by EU parliamentarians, who started the legal action, claiming that American agencies could not be trusted with passenger data.

For the past two years, European airlines have been giving the US Department of Homeland Security 34 pieces of information about each passenger, including name, address, credit card details and phone numbers.

They did so under a deal agreed between all 25 EU governments and Washington, aimed at balancing passenger privacy against the need to combat terrorism. It was reached after aircraft were refused entry to US airspace over concern that they carried suspect passengers.

However, judges in Luxembourg ruled that the deal had no legal basis under European law. To avoid plunging transatlantic routes into immediate chaos, the court said that the annulment would not take place until September 30. Bob Preston, of the British Air Transport Association, said: “If we don’t supply the information to the United States authorities then we’re liable to fines of up to $6,000 per passenger and the loss of landing rights. And if we do supply the data, potentially we’re breaking the law.”

European governments and the European Commission said that they could not immediately see any way through the impasse, although Washington indicated that it would be cooperative. A British official said: “We are very disappointed the European Court of Justice has decided to annul this decision. There is an urgency to this.”

Stewart Baker, the US Assistant Secretary of State for Homeland Security, said: “I am confident that we will find a solution that will keep the data flowing and the planes flying.”

One solution is for European governments to bypass the European institutions and sign one-to-one bilateral deals with Washington. The court made the ruling after an appeal by the European Parliament.

Graham Watson, the leader of the Liberal Democrats in the European Parliament, said:

“Today’s judgment vindicates the four-year campaign to protect the privacy of airline passengers.” Michael Cashman, a Labour MEP on the civil liberties committee, said: “Although there are real concerns about privacy, it is being driven by anti-Americanism.” Geoffrey Van Orden, the Conservative terrorism spokesman, said: “It’s sending a negative message to the US, which will mistakenly get the impression that Europe is not serious about terrorism.”

Pete King, the Republican chair of the Homeland Security Committee in the House of Representatives in Washington, told the BBC: “Sometimes I think European parliamentarians don’t realise the reality of governing.”

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