President Trump has been busily tweeting that there oughta be a rule: “The NFL has all sorts of rules and regulations. The only way out for them is to set a rule that you can’t kneel during our National Anthem!”

This was, of course, just one of his many forays in response to the recent league-wide protest begun by Colin Kaepernick’s kneeling during the anthem to protest inequitable and excessive instances of state force. Yet it seems not to matter what those who are kneeling say their action meant: “We chose to kneel because it’s a respectful gesture,” wrote San Francisco 49ers safety Eric Reid in The New York Times of his and Kaepernick’s decision. “I remember thinking our posture was like a flag flown at half-mast to mark a tragedy.”

No matter: To Donald Trump, kneeling in sorrow is both a sign of disrespect for the rules of the game and a desecration of the American flag. If Trump were just some random armchair grouch, that wouldn’t be so worrisome. But he is not a private citizen; he’s our president, and everything he says carries the weight of that office.

There are at least two grave legal implications to what the president has been urging—one of private law, the other constitutional.

The first concern is that executive power is being used to interfere in contract relations between private parties. Yes, rich owners and their rich celebrity employees, but still: private parties. Trump’s tweeted injunction, moreover, was deployed by a head of state against citizens whose political views he doesn’t like. This resembles the sort of pressure applied by the House Un-American Activities Committee and its Senate counterpart, the Permanent Subcommittee on Investigations, which was chaired by Senator Joseph McCarthy (and whose lead counsel, let it not be forgotten, was Trump’s mentor, Roy Cohn). At least 300 members of the motion-picture industry were blacklisted as a result of that politically motivated purge. Few ever recovered their careers.

Such heavy-handed state influence has a long history of legitimizing discrimination. After all, one shouldn’t have to give up basic civil rights in deference to a service or employment contract. A contractor who fires someone simply for being a Democrat or a Republican, for being gay or a woman—these are all situations that may trigger judicial scrutiny. By the same token, contractors who discriminate unfairly among their customers may trigger the same kind of scrutiny. This latter point will be adjudicated by the Supreme Court in its current term, in a complaint brought before the Court by Jack Phillips, a Colorado baker. Backed by Trump’s Justice Department, Phillips maintains that his religious beliefs prevent him from making wedding cakes for gay couples. Yet permitting him to opt out of antidiscrimination laws would ultimately undermine their application everywhere—department stores, hotels, restaurants, florists, planes, trains, and buses. The long-standing norm of fair and equitable public accommodation would be rolled back to the era of Jim and Jane Crow. As Louise Melling of the ACLU argues, “No bakery has to sell wedding cakes. But if it chooses to sell wedding cakes it can’t turn away some customers because of who they are.” Similarly, terminating the employment of professional athletes for expressing a view that has nothing to do with their job may be construed as a form of discrimination against “who they are.”

The second concern is a matter of constitutional rights. Trump has repeatedly equated “taking a knee” with desecration of the American flag. This is quite a conceptual leap, but it seems to be one that many of his supporters have also made. Trump has further warned that desecrating the flag must have “consequences—perhaps loss of citizenship or year in jail!” Of course, the Supreme Court has ruled more than once that disrespecting or outright destroying the flag isn’t a punishable offense—and expatriation has been deemed “cruel and unusual punishment” even for wartime desertion. It is very settled jurisprudence that, under the First, Eighth, and 14th Amendments, a citizen cannot be alienated without his or her clear and voluntary renunciation of that citizenship. Period.

And yet… President Trump has suggested all sorts of wild things that once seemed unimaginable but that have now or might one day come to pass. So it’s worth thinking about this notion of revoking citizenship for peaceful political protest. After all, the concept of birthright citizenship has been present since the founding of the Republic. Slavery presented a conspicuous exception, and the Supreme Court’s infamous 1857 decision in Dred Scott v. Sandford denied citizenship to any African American, whether slave or free. The 14th Amendment was passed after the Civil War to remedy that constitutional lacuna, and since then American jurisprudence has resisted all efforts to deny certain groups of people citizenship rights if they were born here. Recently, however, Republicans have moved to rewrite or revoke the 14th Amendment in order to deny birthright citizenship to so-called “anchor babies.”

I worry that Trump has even linked taking a knee to the threat of physical danger, speculating that many team owners joined in the league-wide manifestations of dissent because they were “afraid of their players.” Moreover, I cannot easily disaggregate Trump’s unfounded sense of a threatened ownership class from the far right’s conviction that Black Lives Matter should be classified as a “terrorist” organization. It would be ironic if protests against the use of excessive force by police were used to justify expatriating people or banning political movements for being “violent.”

If Trump is right that “most people agree” with him that NFL owners are cowering and kowtowing to the bullying of big black men, then, dear reader, we need to ponder that insinuation with more apprehension and less complacency than that with which the very possibility of Trump’s election was so laughingly dismissed.