The US constitution, and really any constitution, also offers some protections for non-citizens. To wit: the word 'citizen' does not appear once in the first te

The US constitution, and really any constitution, also offers some protections for non-citizens. To wit: the word 'citizen' does not appear once in the first ten articles of the Bill of Rights. Morally, and really from a PR standpoint as well, anything else would have been impossible even at the time of the framers. If you are known for your declaration of "all men being created equal" and possessing "certain inalienable rights" you can't really turn around and say "no, sorry, you're an alien". Voting or residing in the United States isn't generally among the universally recognised human rights and can be separated from, for example, the right to a (fair) trial. Without that, foreigners on US soil, and you everywhere else on earth, would have absolutely no protection and could literally be executed on the whims of some Sheriff or prosecutor. The use of drones for targeted executions is a strangely useful example showing this: only because non-citizens are protected in general did the US need to come up with the fantasy that is its "unlawful combatant" construction.