Activists who are organizing mass marches and demonstrations in cities across America may well be congratulating themselves on the huge numbers of people they can get to turn out to protest efforts in Congress to reduce illegal immigration. No doubt that will impress many in the media and intimidate many politicians. But how these marches will be seen by millions of other Americans is another question entirely. The Mexican flags and the strident assertions of a right to violate American laws are a danger signal to this society, as they would be to any society. The releasing of children from...