My question is NOT about the problems associated with secondary consequences of illegal immigration, such as unemployment of the native workforce. Nor is it about the causes of illegal immigration, such as the hardships faced by people living in a neighboring country, which causes them to cross the border illegally.
I want to look at the issues raised related to interpersonal trust versus the law of the land from a the perspective of duty-based approaches to ethics (e.g. Kantianism).
I think this dilemma is roughly identical to the following: If you have won the trust of a stray dog, is it ethical to turn him/her over to animal-control?
In other words, how do duty-based ethical system resolve conflicts between duties to the state and conflicts between duties to individuals (human or animal) which one is in relationship with?