Constitutional Rights of Non-Citizens:

I've heard many people suggest that the Bill of Rights protects only citizens, and not legally admitted aliens. Some have argued that surely the Framers would not have understood the Bill of Rights as protecting noncitizens.

It turns out, though, that at least one pretty significant Framer -- that would be James Madison -- took the opposite view. Here's Madison, from his Report on the Virginia Resolutions, which criticized the Alien and Sedition Acts of 1798:

Again, it is said, that aliens not being parties to the Constitution, the rights and privileges which it secures cannot be at all claimed by them.

To this reasoning, also, it might be answered, that although aliens are not parties to the Constitution, it does not follow that the Constitution has vested in Congress an absolute power over them. The parties to the Constitution may have granted, or retained, or modified the power over aliens, without regard to that particular consideration.

But a more direct reply is, that it does not follow, because aliens are not parties to the Constitution, as citizens are parties to it, that whilst they actually conform to it, they have no right to its protection. Aliens are not more parties to the laws, than they are parties to the Constitution; yet, it will not be disputed, that as they owe, on one hand, a temporary obedience, they are entitled in return to their protection and advantage.

If aliens had no rights under the Constitution, they might not only be banished, but even capitally punished, without a jury or the other incidents to a fair trial. But so far has a contrary principle been carried, in every part of the United States, that except on charges of treason, an alien has, besides all the common privileges, the special one of being tried by a jury, of which one-half may be also aliens.

The Supreme Court has endorsed Madison's view at least since Wong Wing v. U.S. (1896) as to the criminal procedure provisions, and in Yick Wo v. Hopkins (1886) (also unanimously) as to the Equal Protection Clause racial equality principle. Aliens might be deportable for their speech (see here for more on that question), but they can't be otherwise punished for it, nor can they be criminally prosecuted in the civil justice system without the normal constitutional protections. (The question of when military justice may be applied to them is a separate and complicated issue, and one that may potentially relate to citizens as well as aliens.)

Now I'm not a historian of the matter, and it may well be that the matter was unclear. Certainly Madison was arguing against people who took the contrary view; perhaps they were in the solid majority on this. But at the very least one shouldn't just casually assume that the Bill of Rights must of course apply only to citizens, when the principal drafter of the Bill of Rights took the opposite view.