"The "law" that these folks really broke, was being Arab looking or from an "arab country". "

I disagree. There are many American citizens and legal vistors who are from arabic descent.



"Much easier to round up people based on their country of birth, expecially when they are not US citizens and who are therefore not subject to the US constitution and Us laws."

True.

I guess overstaying your visa would be more like violating policy rather than law.