I’m filing this under non-tariff barriers:

All cargo going into the US on ships would have to undergo thorough screening at foreign ports under new legislation agreed by key congressional committees, in a move attacked on Wednesday by the shipping industry as a recipe for chaos…

Erik Autor, vice-president for international trade at the National Retail Federation, said there would be significant technical challenges in meeting the bill’s requirements…

He questioned, for example, whether the Department of Homeland Security had the resources to examine promptly the millions of images that would be created annually of containers scanned at overseas ports.

“We still say that there are potentially a great deal of challenges in order to implement this mandate – and challenges that are not going to be overcome any time soon,” he said

Mr Autor warned the time taken to scan containers would slow down handling at many ports in a system already prone to congestion. [FT]

Is 100% screening feasible? See this really long article for details of the debate. I don’t see a definitive answer.