What’s Wrong with Improperly Entering the United States?

Abstract US law forbids foreigners from entering the United States without its approval. Violation of such law is subject to criminal punishment, which raises the question of whether the violation is morally wrong. In this Article, I will demonstrate that even under seriously unfavorable assumptions—(1) the United States is morally permitted to keep foreigners out and (2) there exists a moral obligation to follow some mala prohibita laws—it is nevertheless morally permissible for foreign citizens to cross the border without the approval of the United States. The law prohibiting entry without approval is US malum prohibitum law, and moral obligations to follow US mala prohibita law attach to US citizens, not foreign citizens.