It is a question that several circuit courts have struggled with. Does the Second Amendment protect unauthorized aliens within the borders of the United States? The answer, according to a compelling argument from the Seventh Circuit Court of Appeals, is yes.
On August 20, 2015, the court ruled in the case of United States v. Meza-Rodriguez (7th Cir. 2015). The defendant in this case was Mariano Meza-Rodriguez, a citizen of Mexico whose parents brought him to the United States as a young child. He remained in the United States from that time without ever becoming a citizen or a documented resident alien.