Can a private citizen violate the US Constitution?

I don’t think this is quite accurate. AFAIK, there’s no statute that bars the government from infringing upon, say, the First Amendment, but injunctive relief is available for such a violation as a matter of course. The Bivens case set forth limited circumstances where a plaintiff could bring a civil action against a government employee arising solely from the Constitution. The Miranda rule articulated a purely constitutional remedy. And pre-Miranda, wasn’t it commonly accepted that an individual whose Fourth Amendment rights had been violated had a constitutional civil right of action against the law enforcement officer?

You’d be seeking an injunction in this situation - a legal ruling that you were not your neighbour’s slave.

And while we’re discussing a hypothetical here, this pretty much happened in real life. Mum Bett was a slave in Massachusetts in 1780. Massachusetts’ new Constitution was enacted that year and it said “All men are born free and equal, and have certain natural, essential, and unalienable rights; among which may be reckoned the right of enjoying and defending their lives and liberties; that of acquiring, possessing, and protecting property; in fine, that of seeking and obtaining their safety and happiness.”

Bett heard this and asked if the law said everyone was free, then how could she be a slave? She found a lawyer and took it to court and the judge and jury agreed with her. They ruled that Bett couldn’t be a slave in Massachusetts. Bett changed her name to Elizabeth Freeman and lived the remaining forty-nine years of her life in freedom.

But while Bett was declared to be a free woman nobody charged her former owner, John Ashley, with any crime.

The first one seems pretty patently something a private citizen cannot do. It’s a limit on government. The only way you could infringe someone’s right to keep and bear arms is by being a governing body that passes a law restricting it, or by being a governing actor who “lawfully” confiscates arms. How could a private citizen do that? If you take someone’s gun as a private citizen, that’s just theft, not a breach of their right to bear arms.

I admit that as a practical matter it’s always been interpreted as a restriction on government action. I’ll even go further and say that was probably the original intent.

But that’s not how it’s written. Compare the text of some amendments:

“Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.”

The right of citizens of the United States to vote shall not be denied or abridged by the United States or by any State on account of race, color, or previous condition of servitude.

The right of citizens of the United States to vote shall not be denied or abridged by the United States or by any State on account of sex.

They explicitly state that these laws apply to “Congress” or “the United States” or “any State”.

Now look at the Second Amendment:

A well regulated militia being necessary to the security of a free state, the right of the people to keep and bear arms shall not be infringed.

Nothing in the text that limits its application to the government. The law doesn’t say “Congress shall make no law infringing the right of the people to keep and bear arms” or “The right of citizens of the United States to keep and bear arms shall not be infringed by the United States or by any State.” And the fact that language like that is used in other sections implies that exceptio probat regulam in casibus non exceptis.

You two are right here, of course. I was focused on the idea of criinal acts in violation of the Constitution itself. Civil violations that can given injunctive relief certainly exist – are relatively common, if one includes governmental actors.

It is criminal to violate a persons civil rights, if the intent necessary to establish the mens rea is present, as 18 USC 242 points out.

In my state, Ohio we have a statute; Interfering with Civil rights; it is criminal if a person is deprived of thier Civil Rights, state or federal. As you see the word KNOWINGLY here, that is the culpable mental state required to get a conviction.

2921.45 Interfering with civil rights.
(A) No public servant, under color of his office, employment, or authority, shall knowingly deprive, or conspire or attempt to deprive any person of a constitutional or statutory right.

A Bivens action merely asserted a federal claim against federal agents, as a counterpart of the Civil Rights Act of 1871, codified at 42 USC 1983.

A state law tort claim always existed, but Bivens clarified that federal courts had jurisdiction for 4th AM violations, not just state courts. Bivens was handed down in 1971. The 4th AM was not made applicable to the states until 1949.

I believe NY has equivalent laws (although I’m not bothering to look them up.) I was writing the Wikipedia article on Engblom v. Carey and part of the basis of the decision was whether the state had knowingly violated the Third Amendment - in this particular case, the judge acknowledged that what the state did probably was a violation of the Third Amendment but the state wasn’t liable because there was virtually no established case law on what the Third Amendment prohibited so the state couldn’t know if what they did was a violation.