slavery
driftglass gets it right:
In 1861 the South was prosperous specifically because of the forced labor of four million brown people who were reviled, exploited, abused and utterly necessary.
In 2006, America is prosperous specifically because of the peonage-cheap, illegal labor of twelve million brown people who are reviled, exploited, abused and utterly necessary.
We tolerate with a wink-and-a-nudge a system that simultataneously criminalizes a labor force of twelve million to keep them underground and terrified, and then carefully extracts their labor for pennies.
Any social policy which doesn’t confront immigration on those terms will fail and fail badly because, in the end, we really only have two choices: Either a renegotiation of the social contract to pay working people a living wage, or an open recognition that we will forever rely more and more on cheaper and cheaper labor to remain spoiled and Holy.