Yes, indeed, immigrants are obliged to obey the laws of the countries they enter, just as all are obliged to obey the commandment and not to steal.
But just as the injunction not to steal is superseded by dire need in the case of the starving man or the man with a starving family, there are exceptional circumstances in immigration.
And that's what I was talking about:
“The illegal immigrant who comes to our country truly out of final desperation objectively breaks the law, but it may be that he does not sin.”
Certainly, the refugee from war who, to avoid death, crosses the international frontier between two states and enters illegally into a second state, objectively breaks the law of the second state. But I don't think most folks think that people in these circumstances have sinned, even though they may have been breaking the law of the land that they entered.
The question is whether or not the circumstances are sufficiently dire that objectively breaking the law becomes the final way one may preserve life and limb. Whether or not that is the case with any, or with a large number of illegal immigrants is beyond my knowledge. I'm only showing that Mr. Rubio is on the right track here:
“Hypothetically, if Marco Rubio were not an American citizen and could not provide food for his family, he says he would cross the border illegally to come to the United States.”
If it is possible to contact legitimate authorities without risking further or additional danger, one should do so. One should arrange to return as soon as is possible and, while a refugee, do as much as possible to contribute positively.
I still think that one would need to be conscious of the potential sinfulness of the act. I don't know if Rubio is Catholic, but even the bishops rarely mention the responsibilities of the immigrant.
Forgot to say that, however, I think this hypothetical has of virtually no relevance to the current immigration debate.