[antonvs]

> Turns out Mexico doesn't legally require a passport for entry

This isn't true. See e.g. https://consulmex.sre.gob.mx/washington/index.php/ligavisos/... :

> "All foreigners, regardless of their nationality, are required to present a valid and not expired passport or travel document when entering Mexico (traveling by air, land or sea)."

What you may have observed is Mexican border control at a small crossing may not enforce that requirement.

[mothballed]

  Article 11 [Mexican Constitution]

  Every person has the right to enter and leave the country, to travel through its territory and to move house without the necessity of a letter of safe passage, passport, safe-conduct or any other similar requirement. In the event of criminal or civil liability, the exercise of this right shall be subject to the judicial authority. Relating to limitations imposed by the laws on immigration and public health, or in respect to undesirable aliens residing in the country, the exercise of this right shall be subject to the administrative authority.

Every person has the right to enter the country without a passport. There are ways for the authorities to get around it and fuck with people found in the interior without it (says subject to administrative authority for immigration, but they're explicitly constitutionally barred from requiring anything like a passport) , but ultimately it's unconstitutional to make a law requiring it. This trumps the aspirational hearsay provided by the consulate and explains why none of the consulate advice is able to cite where this supposed "requirement" comes from. The consulate either was mistaken or wrote that because it will really suck to leave the country without it and they don't want to deal with the fallout.

https://www.constituteproject.org/constitution/Mexico_2015#s...

[antonvs]

> none of the consulate advice is able to cite where this supposed "requirement" comes from.

It comes from Mexico's immigration law, Ley de Migración: https://www.diputados.gob.mx/LeyesBiblio/pdf/LMigra.pdf

Here are a couple of relevant sections, from pages 16 and 15 of the above document, respectively:

For foreigners to Mexico:

    Article 37. To enter the country, foreigners must:
    I. Present the following documents at the immigration inspection checkpoint before the Institute:
    a) A passport or identity and travel document that is valid in accordance with applicable international law; and
    b) When so required, a validly issued and current visa, pursuant to Article 40 of this Law; or
    c) A residence card or authorization for the immigration status of regional visitor, border worker visitor, or visitor for humanitarian reasons.

For Mexicans:

    Article 36. Mexicans may not be deprived of the right to enter national territory. To this end, they must prove their nationality, in addition to complying with the other requirements established in this Law, its Regulations, and other applicable legal provisions.
    Mexicans shall prove their nationality using one of the following documents:

    I. Passport;
    II. Citizen Identity Card, Personal Identity Card, or its equivalent;
    III. Certified copy of a Birth Certificate;
    IV. Consular Registration Card;
    V. Letter of Naturalization; or
    VI. Certificate of Mexican Nationality.

I'm not interested in debating whether this *law* is compatible with Mexico's constitution. That has in fact been litigated, and Mexico's Supreme Court has "recognized the constitutionality of the immigration authority's power to request documents from foreign nationals to verify their legal entry, stay, and departure from the country." (https://tirant.com/mx/actualidad-juridica/noticia-inconstitu...).

The point is, that's what the prevailing law says, and that's what's generally practiced at borders, consulates, and embassies.

> The consulate either was mistaken or wrote that because it will really suck to leave the country without it and they don't want to deal with the fallout.

Ah yes, I'm sure the entire legal apparatus of the country of Mexico is just winging it, whereas you, noble HN commenter, have sussed out the true facts. Or perhaps you just heard and believed a story from some rando at a border crossing.