From  Eugene Volokh at the Volokh Conspiracy:

In today’s United States v. Portillo-Munoz, a divided Fifth Circuit panel holds that illegal aliens don’t have Second Amendment rights because they’re not part of “the people,” and suggests that they may lack Fourth Amendment rights as well. (The same logic might apply to the First Amendment’s Petition Clause, which also mentions a right of “the people” to peaceably assemble and petition the government for a redress of grievances.) Here’s the core analysis from the majority:

The individual laying claim to the Second Amendment’s protections in Heller was a United States citizen, so the question of whether an alien, illegal or legal, has a right to bear arms was not presented, and the Court took care to note that it was not purporting to “clarify the entire field” of the Second Amendment. However, the Court’s language does provide some guidance as to the meaning of the term “the people” as it is used in the Second Amendment. The Court held the Second Amendment “surely elevates above all other interests the right of law-abiding, responsible citizens to use arms in defense of hearth and home.” Furthermore, the Court noted that “in all six other provisions of the Constitution that mention ‘the people,’ the term unambiguously refers to all members of the political community, not an unspecified subset” before going on to say that “[w]e start therefore with a strong presumption that the Second Amendment right is exercised individually and belongs to all Americans.” The Court’s language in Heller invalidates Portillo’s attempt to extend the protections of the Second Amendment to illegal aliens. Illegal aliens are not “law-abiding citizens” or “members of the political community,” and aliens who enter or remain in this country illegally and without authorization are not Americans as that word is commonly understood.

More Volokh, including the opportunity to comment.
More Fifth Circuit, [PDF]including dissents.