The Constitutional rights of foreign foreign nationals is complicated [1]. Long story short, the Constitution may not protect them as fully as it does U.S. persons (Americans and foreigners on American soil).
[1] https://scholarship.law.georgetown.edu/cgi/viewcontent.cgi?a...
> ... it is not surprising that many members of the general public presume that noncitizens do not deserve the same rights as citizens. But the presumption is wrong in many more respects than it is right. While some distinctions between foreign nationals and citizens are normatively justified and consistent with constitutional and international law, most are not.
Non-citizens don't have a fundamental right to vote, or to enter the country. Non-citizens cannot hold federal office. Non-citizens accused of crimes may be held in jail pending their trial in situations where citizens would be free pending trial. But that's a pretty short list. In fact nearly all fundamental freedoms of the Bill of Rights (speech/press/religion/assembly) and rights to a fair trial apply to citizens and non-citizens alike.
That makes no sense whatsoever to me. Where in the US Constitution is this restriction on the First Amendment?
Mind you, the First Amendment and freedom of speech are related, but not the same, and one can easily argue that freedom of speech is universal, but not the American Constitution.
But, oddly, as not applying fully to acts of the American government taken outside of the borders of the United States, which is why Gitmo is used for sketchy War on Terror detentions, and not any place on sovereign US territory rather than territory notionally leased by the US from a foreign sovereign.
Johnson v Eisentrager (1950) is the landmark case, but its been fleshed out subsequently (and most of those decisions have narrowed the apparent gap in the Constitution it opened up), largely in response to the decision to use Gitmo as a get out of law free card. But the existence of that decision is why Gitmo got used.
And given the split on those decisions limiting Eisentrager, I wouldn't want to see what the current court would do with cases in that area...
The laws of the EU or Russia certainly do apply to Americans in EU or Russia. In fact they apply to anyone within the respective jurisdictions.
[1]: https://inter-american-law-review.law.miami.edu/u-s-constitu...