Mexico’s first Penal Code (published in 1871) which entered into force in 1872, made no reference to the criminalisation of sodomy or any other consensual same-sex act between adults.
Nevertheless, LGBTQ people could be prosecuted under the vague language of article 787 (Third Book; Title 6 'Violations against family order, public decency, or traditional customs'; chapter II 'Offences against public morals or good manners'), which never mentioned any sexual orientation or gender identity. The penalty included arrest and a fine if the alleged 'indecent act' was committed either in a public place (with or without witnesses) or in a private place.
The first known reference of the application of this article towards LGBTQ people dates from November 1901 when the scandal of the 'baile de los cuarenta y uno' (the 'Ball of the Forty-One') occurred. Police illegally raid a private home in Mexico City where 41 men (some of them dressed in women's clothing) from the upper classes of the Mexican society were attending am event. The identity of the suspects was never disclosed, but according to some sources, there are some press articles at the time that state some of them could be conscripted into the army and sent to Yucatán to public works. This was as the Caste War against the Mayan Indigenous rebels was finalising. There are seven names listed in the records of the Supreme Court who filed a writ of protection against their conscription to the army because homosexuality was not illegal in Mexico at the time. Hence, the charge was simply replaced (crime against decency), but the punishment didn't change.

This Penal Code was replaced in 1929.

The congress of Mexico’s northeastern border state Tamaulipas has voted to recognise same-sex marriage, making it legal across the country.

Becoming the last of the country’s states to do so, Tamaulipas amended the state’s Civil Code on Wednesday, setting off cheers of “Yes, we can!” from supporters of the change.

In Mexico, there are no laws restricting to discussion or promotion of LGBTQ+ topics.

In 2009, the Supreme Court of Mexico established in its Judgment No. 6/2008 (2009) that the right to personal identity and free development of personality includes the right to gender identity and to "sexual reassignment", which obliges states to provide access to the "rectification of name and sex legal markers".
In 2018, the Court issued Judgment No. 1317/2017 (2018) where it analysed the most appropriate procedure to guarantee "sex-gender rectification in the Civil Registry". In summary, this judgment concluded that the type of authority (judicial or administrative) before which the procedure is conducted is irrelevant as long as the nature of the procedure is materially administrative. Specifically, it must (a) be comprehensive; (b) be based on free and informed consent, with no medical, psychological and/or pathologising requirements; (c) be confidential; (d) be expeditious and free of charge; and (e) it must not require surgical or hormonal treatments. Despite this, various Mexican have not unified their regulations and, in many cases, continue to require judicial processing and all sorts of evidence.

In 1998, Mexico adopted the ICD-10 classification, which contains codes for diagnosing transsexualism in adulthood and childhood, which authorize the initiation of medical transition.

Non-binary Mexican citizens can choose to have an X as their gender marker rather than choosing male or female.

However, other IDs are handled on a state level basis and not all of them allow the X gender marker.

Since 2011, Article 1 of the Political Constitution of the United Mexican States (1917) (federal constitution) prohibits discrimination based on “sexual preferences”. 3 out of 32 subnational jurisdictions bans discrimination based on gender identity in its State Constitutions. Article 1(3) of the Federal Act to Prevent and Eliminate Discrimination (2003) includes “sexual preferences” as one of the prohibited grounds of discrimination

Most of Mexico's states have enacted laws that ban discrimination based on sexual orientation or sexual preference, as well as gender. Many states also explicitly ban discrimination based on gender identity in local laws.

At the level of the federal government authorities, Article 1(3) of the Federal Act to Prevent and Eliminate Discrimination (2003) includes “sexual preferences” as one of the prohibited grounds of discrimination. This law applies to housing as per Article 9(XXI). Gender identity is not explicity mentioned

There is no federal law allowing for joint adoption and second parent adoption by same-sex couples. Adoption is only permitted for same sex married couples in 21 of the 31 Mexican states and Mexico City

There's no ban on intersex infant surgery in Mexico

LGB people can serve in the military openly, Transgenders Can’t

Conversion therapy is a federal offence under Article 209 Quintus of the Federal Penal Code (Código Penal Federal) and Article 465 Ter of the General Health Law (Ley General de Salud).

Conversion therapy is defined as any treatment, service, therapy, or practice intended to obstruct, restrict, impede, diminish, annul, or suppress sexual orientation or gender identity/expression.

Those liable under the law include anyone who practices, conducts, imparts, applies, forces, or funds such activities.

Sanctions include:
- 2 to 6 years in prison and a fine of 2,000 UMA (Unidad de Medida y Actualización, a unit updated yearly based on inflation. In 2024, 2,000 UMA exceeded $11,000 USD).
- Sanctions are doubled if the victim is a minor (-18), an elderly person (+60), or a person with a disability; or if the perpetrator is a public/government employee, or they have any relationship with the victim (such as family member; or employer, teacher, medical professional, doctor, nurse, or psychologist). Additionally, the latter will face professional dismissal, disqualification, and suspension (1 to 3 years or equivalent to the prison sentence).
- Sanctions are further doubled if any kind of violence (physical, psychological, or moral) is used against the victim.

Illegal with a minor under 12, ambiguous rulings observed 12-18, universally legal 18+.