How terrorists can bypass immigration

Like many Canadian airports it is now possible to pass through US immigration in Dublin when flying to the states. But unlike the Canadian scheme the Irish one does not cover customs.

This leads to a major security problem on arrival in Chicago. The airport is built for only two types of arrival: domestic and international. There is no third category for passengers who have passed immigration but not customs.

So when passengers from Ireland arrive at Chicago they mix with the other passengers who have not passed through immigration and then present their stamped customs declaration form to bypass the queues at immigration.

The customs form has no binding to the passenger presenting it. So all it takes to bypass immigration is to arrange to fly to Chicago on an international flight which is scheduled to arrive before a flight from Ireland, hang out in the rest rooms until the Irish flight is in, then present a customs form with a fake stamp to bypass the immigration desk. Alternatively put a passenger with a US passport on the flight from Ireland, on arrival in Chicago they pass their customs form to the terrorist and then pass through immigration as normal.

It would probably cost something to refit Chicago and other airports to handle this situation securely. But the costs are small compared to the $22 billion or so that RealID is going to cost.