Originally Posted by
zkzkz
There's no violation of immigration regulations because they're both US citizens and have a right to enter. You could argue it was a federal crime of not obeying the officers' instructions (in the form of the signs and instructions) but that's would be the same federal offense as using a cell phone in line.
I am not sure if you are breaking immigration regulations, but I think anyone entering the US is required to undergo a Customs search.