If you’re a British citizen flying to the United States, you better hope that there’s nothing suspicious on your credit card bills:

Britons flying to America could have their credit card and email accounts inspected by the United States authorities following a deal struck by Brussels and Washington.

By using a credit card to book a flight, passengers face having other transactions on the card inspected by the American authorities. Providing an email address to an airline could also lead to scrutiny of other messages sent or received on that account.

The extent of the demands were disclosed in “undertakings” given by the US Department of Homeland Security to the European Union and published by the Department for Transport after a Freedom of Information request.

These measures will be justified by pointing to September 11th and last summer’s arrest of British Muslims involved in a plot to bomb aircraft headed to the United States, no doubt. But it is already clear that the information collected will be used for far more than just combating terrorism:

Not only will such material be available when combating terrorism but the Americans have asserted the right to the same information when dealing with other serious crimes.

And the information will be available for use long after the person in question has left the United States:

Initially, such material could be inspected for seven days but a reduced number of US officials could view it for three and a half years. Should any record be inspected during this period, the file could remain open for eight years.

Material compiled by the border authorities can be shared with domestic agencies. It can also be on a “case by case” basis with foreign governments.

Washington promised to “encourage” US airlines to make similar information available to EU governments — rather than compel them to do so.

And the line between “compel” and “encourage” isn’t bright at all. I would expect similar information about American citizens flying abroad to be shared with foreign governments soon, if it isn’t happening already.

What is unclear is how monitoring this much information about this many people is going help in any significant respect in stopping a real terrorist from getting into the country. Compared to the massive violation of privacy and civil liberties that this involved, it would appear that the benefits of the program are really quite minimal.