Someone insisted that, in the United States, "illegal alien" is a legal term.
PolitiFact took a long and careful look at that claim, concluding:
The term appears--yet scarcely--in federal law. Best we can tell, though, no law defines the term as referring to all individuals living in the U.S. without legal authorization. Where the term does appear, it’s undefined or part of an introductory title or limited to apply to certain individuals convicted of felonies.
PolitiFact rated the claim "Half True".
The following analogy arose from that discussion. As an analogy, it might support the idea that the US government can adopt a contentious term of art for its own purposes, but its power to impose that terminology upon its states and citizens is limited.
“Gulf of Mexico” is the legal term for that body of water.
It was. Now it isn’t. What’s your point?
According to the
International Hydrographic Association, which is recognized as the competent international authority when it comes to nautical charting, its name is the Gulf of Mexico.
The United States is one of IHO's 102 member states. IHO Resolution 8 ("Treatment of Names of Features beyond a Single Sovereignty") recommends "that where two or more countries share a given geographical feature (such as, for example, a bay, a strait, channel or archipelago) under a different name form,
they should endeavour to reach agreement on fixing a single name for the feature concerned." On the other hand, the IHO cannot compel agreement. Its member states retain the right to decide which names will be used by their own bureaucracies and, in the more autocratic states, by their populations at large.
On his first day in office, President Donald Trump signed
Executive Order 14172, which requires US federal agencies to refer to the Gulf of Mexico as "Gulf of America" and Denali as "Mount McKinley". Private entities and individual states of the United States are not bound by that executive order. The state of Alaska, for example, still recognizes "Denali" as the legal name of that mountain. The governors of Florida and Texas now speak of the "Gulf of America", but polls show an overwhelming majority of Americans opposed to that name change, both nationwide and in Florida. (As for Texas, I am not aware of any relevant polls.) Despite some rather heavy-handed
arm-twisting by the Trump administration, the Gulf of Mexico continues to be known by that historic name (c 1550) in common usage. From the few court rulings that have been issued so far, it appears the Trump administration will be unable to overcome the First Amendment right of its people to refer to the Gulf of Mexico as the Gulf of Mexico.
Outside of the United States, the executive order has no legal force whatsoever. Most countries have simply ignored it. Mexico and the United Kingdom have said they will ignore it.
While checking on this, I learned that the Gulf of America was named after Amerika, which was a ship commanded by Nikolay Muravyov-Amursky. In 1972, the Gulf of America was renamed. It is now part of Nakhodka Bay.