Immigration Ethics + Policy

Do countries have an obligation to accept immigrants or refugees?

The EU is facing an enormous problem in dealing with the recent surge of immigrants from middle eastern countries. One recent proposal by the EU will allow Greece to begin sending back refugees that arrive from Turkey. However, there are enormous complexities involved in attempting to solve such a massive migration crisis, which makes policy decisions incredibly difficult. What are the arguments for and against allowing immigrants? What policies would have a positive practical effect given the current situation? And, as above, do countries ever have a moral obligation to accept immigrants or refugees?

How do we remain humane in our treatment of those looking for asylum and protection from the circumstances from which they are fleeing, while at the same time respecting the rights and livelihoods of existing citizens?