The transfer to the US of EU travellers’ Passenger Name Record (PNR) data – the information we give the airline for booking purposes – has been happening for over a decade. MEPs including me have been battling since then to control the terms on which that transfer takes place in order to build in adequate data protection, and we have secured considerable improvements.

It is important to recall that the US has a sovereign right to impose whatever conditions it wishes on airlines and passengers entering its territory and to refuse entry, or landing rights to planes, if those conditions are not met. The transfer of PNR data would therefore continue whether there was any EU legal basis or not, since airlines are obliged under US law to transmit it to the US authorities.

In a controversial vote, MEPs recently approved by a considerable majority (409 in favour, 226 against with 33 abstentions) a new EU-US PNR agreement to replace the existing 2007 one which has never been ratified but which has applied provisionally. I have been much involved in the issue as a member (since 1999) of the European Parliament’s Civil Liberties committee and also as Vice-Chair of the delegation to the US, and have sought to facilitate transatlantic travel with the least possible invasion of privacy.

I was one of the nearly one-third of ALDE group MEPs who voted in favour of the new agreement since it imposes legal protections which would otherwise be absent. I would much rather PNR data was not made available, but as MEP for London I have a high number of constituents who fly occasionally or even regularly to the United States and am very conscious of the potential disruption without an agreement. An individual can of course decide not to make the trip.

I voted yes because, while readily acknowledging that the new deal does not meet all the demands of MEPs, it provides better safeguards than the existing 2007 agreement and I could not see how we were going to get a better bargain in any of the alternative scenarios. I knew a rejection would create uncertainty or even less acceptable terms.

In the immediate aftermath (of a rejection) it would mean falling back on the worse 2007 agreement that MEPs declined to consent to, which could open airlines to legal challenge on grounds of violation of EU data protection laws, and possible flight disruption. Alternatively it would leave the field open to a plethora of bilateral accords with Member States that the EU would be unable to control and that would most likely be weaker because of the United States’ ability to divide and rule.

There is certainly no political will in the US to go back to the drawing board and renegotiate the agreement for what they see as the fifth time. Even if President Obama had any such willingness, Congress would not let him do so since it has been sold as essential to counter-terrorism and security operations. This is, after all, election year and Romney could just win. Hoping for better negotiating conditions was not a realistic strategy.

Approval of this EU agreement gives us a platform on which to build a better one. Whether the 2007 agreement continued to apply or the US got bilateral deals with Member States, the safeguards would have been weaker and MEPs could have lost the chance to be involved at all. The European Parliament will now exercise monitoring and call for reviews, and we have in Cecilia Malmstrom, a Liberal Home Affairs Commissioner, whose pledge to keep an eagle eye on US respect for safeguards is credible.

I would just ask those MEPs who voted against the new agreement, or other critics, to explain what alternative they envisaged. So far I have not heard a credible one.

* Sarah Ludford is London MEP and the Liberal Democrat European spokeswoman on justice & human rights. She is a leading member of the European Parliament's civil liberties, justice & home affairs committee.