Demanding that government solve the "illegal immigrant problem" has become a popular pastime for attention seeking media products and scheming politicians. While such demands are distressingly effective in serving the ulterior motives of the advocates, they have been, and will always be, the worst possible alternative for our free society.
It would be very costly for the government to find and deport the millions of invaders in our midst - in both monetary terms and further erosions of individual liberty. The excessive costs, not to mention the near impossibility of such deeply flawed government programs succeeding, indicate that a different approach - or even a different question - is required.
It seems to me that the only possible cost effective approach is systemic - to solve the problem at its source. The core problem is that it's all to easy for people who don't share our common culture to exist within our culture. It follows that the key to a meaningful solution would be to restore America to the kind of place that isn't attractive to the kinds of people who are incompatible with our common culture.
On an individual level, American citizens have a long and honorable history of exceptional generosity to those in legitimate need. We also have a well established tradition of accommodating ethnic diversity - perhaps at times a bit reluctantly, but ultimately more effectively than any other society in human history. So the problem isn't that Americans are insufficiently compassionate or tolerant. The problems start when government intrusions deprive individual citizens of control over their personal generosity and tolerance. It's only when chronically incompetent government gets involved that altruistic charity becomes the sociopathology of subsidized irresponsibility, and enlightened tolerance of other cultures gets perverted into criminalizing respect for our own.
It seems to me that we could make a major start in solving multiple problems by restoring respect for the clear prose and intentions of the 9th and 10th Amendments - which would in turn eliminate at least federal involvement in social services.
Restoring the fundamental right of individual freemen to freely associate - or not associate - as suits their individual tastes and preferences, would also restore the power of a free society to defend itself. This of course isn't a perfect solution - irrational or even malicious discrimination can also result if the level of "operative wisdom" among the general public is insufficient. But like much of our common culture, "allowing" free individuals to live according to their own consciences is overall the least harmful/most effective alternative. The key in this area as well as most others, is a well informed and aware citizenry that fully understands their own enlightened self-interest.
I think willingness to make a good faith effort to adopt our common language is the single best metrics for filtering potential Americans from enemy invaders. It's absolutely necessary that the citizens of a free voluntary society be able to freely communicate. If we can't talk to each other, we certainly can't participate in a mutual exchange of views, or engage in informed interactions within a free market economy. Those who want to join our nation should be willing to learn at least enough of our common language to be a functional participant in the culture they seek to join.
Bilingualism is a major threat to the cohesiveness of society. It by definition creates communication barriers between citizens, and communication barriers inevitably create artificial divisions in society. Encouraging both immigrants and invaders to continue using the languages of their former cultures, obstructs their assimilation into our common culture - while perversely requiring assimilated members of our common culture to learn foreign languages in order to deal with a persistent and growing hostile alien subculture expanding within our midst.
The best solution for the alien invasion threatening to overrun our nation, is for Americans to become again American, and in the process restore America's common culture as both the definition and necessity for surviving within our borders.