http://www.owl232.net/papers/immigration.htm
I now find this to be a very interesting and subtle ethical question
3.6 Social Peace
When large swathes of the work force suffer falling income sure to competition from immigrants, anger will rise to dangerous levels.
3.7 Maintenance of Social Capacity for Self-Governance
Rule of law through government institutions, rather than by an elite of cronies through hired thugs, is possible only under certain conditions. Foremost of these being: 1) Engagement of citizens in government, going beyond the minimum of showing up at a polling booth every four years, and 2) Sufficient education to understand what's being voted upon.
Though both of these are questions of degree rather than Boolean propositions, both nevertheless remain requirements of existential gravity for any free society.
The election of 2016 shows just how imperiled 3.6 and 3.7 have become here in the United States.
The author, writing back in 2010, lacked the 2016 evidence.