While reading this Travel SE question, an answer cited this website about Mexican gun laws which states the following (emphasis mine):

Remember, once you cross the border with a firearm or ammunition it is too late! Ignorance of this law will not get you leniency from the police. You will be arrested and sent to jail. Also, the Mexican judicial system is governed by Napoleonic Law which states that you are presumed guilty and must prove your innocence, the opposite of the U.S. laws.

The American consulate in Tijuana, Mexico also posts a similar warning on their official website (emphasis theirs):

Mexico's civil law system is derived primarily from Roman law and the Napoleonic Code and focuses more on the text of actual laws than on prior court decisions. [...] For an accused person, one of the most critical differences is that under Mexican criminal law, the accused is essentially considered guilty until proven innocent.

Is it true that one is guilty until proven innocent in Mexico? Does this have anything to do with Napoleonic law?

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    is the american consulate not an accurate source, or rather is there a reason we would be skeptical of the wording by the consulate? It is essentially the consulates job to look out for american citizens in mexico.
    – Himarm
    Commented Aug 19, 2015 at 13:19
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    Mexico is a signatory of the Universal Declaration on human rights which requires that one be presumed innocent.
    – March Ho
    Commented Aug 19, 2015 at 13:23
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    @DavePhD: Note how that article qualifies the statement with "in practice" (and actually, the text from the consulate in Tijuana also qualifies the statement with "essentially"). Like this, the statement moves from an absolute fact that is somehow based on a concrete legal rule to something that might just as well be an alarmist interpretation. In particular, note how the consulate's text first states "essentially guilty until proven innocent", and then continues to explain (?) this by pointing out that bailing people out of investigative custody is more complicated and that some things ... Commented Aug 19, 2015 at 13:32
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    @MarchHo: Well, the USA signed that declaration as well, and you're presumed innocent until proven guilty in trial there -- unless you're accused of being a terrorist, in which case you're just left incarcerated and interrogated somewhere for years without a fair and public trial. Not to diss the USA specifically, it's just another prominent example of signatory states ignoring the UDoHR at their convenience.
    – DevSolar
    Commented Aug 19, 2015 at 16:18
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    @slebetman: And now we're back to criminal, not civil. That's not a presumption of guilt. The prosecution always makes its case first. If the court gets the evidence in advance, that's just...the court getting the evidence in advance. The evidence still has to prove that you were speeding. Absent evidence, there's no case to answer. (That happens: You say "I want a court date," the date comes up, the cop is busy and can't attend; automatic acquittal.) Even if the cop turns up and testifies (testimony is evidence), without supporting evidence (logs from radar gun, etc.), it's an acquittal. Commented Aug 20, 2015 at 5:13

1 Answer 1


Yes but it is being changed.

There were a few well-publicized cases which caused public outrage and prompted changes.


Mexico is poised to change its criminal justice system from one that presumes guilt at trial to one that presumes innocence, effective 2016. If this reform is implemented and the new presumption of innocence is taken seriously, it should lead to important changes in police practices and trial procedures that could prevent miscarriages of justice like the one depicted in the documentary. While one can think of other reforms that would improve the integrity of Mexico's criminal justice system, this single change has the potential to accomplish much.

~Charles D. Weisselberg, Shannon C. Turner Professor of Law, University of California, Berkeley, School of Law

EDIT: O.R.Mapper points out that the mexican constitution was amended in 2008 "protecting the innocents" though in the context I'm not certain if that implies a right to presumption of innocence or if there's just some lag implementing it.

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    I suppose one needs to decide between the letter and the implementation of the respective laws, and maybe the question is a bit unclear in that respect. For instance, the Mexican Constitution (from 1917, last revised in 2015) declares basic principles for trials such as "protection of the innocent" being one of the objectives of a criminal case, "prosecution has the burden of proof to show that the accused is guilty" in court, and "the judge will only convict [the accused] if he or she is convinced that the accused is guilty". Commented Aug 19, 2015 at 14:07
  • Any more recent links on this? This is from 2010...
    – user541686
    Commented Aug 20, 2015 at 6:03
  • @Mehrdad: Well, the secondary source from 2010 cited in this answer seems to be contradicted by the primary source I cited that has been valid since 1917 and is still valid in 2015 (even though that primary source might of course be overridden by more specific primary sources). I hope someone with more insight into the Mexican legal system (well, preferrably, someone from Mexico?) will be able to clear this up. Commented Aug 20, 2015 at 6:55
  • @O.R.Mapper Searching for "innocent" or "innocence" in the english translation oas.org/juridico/mla/en/mex/en_mex-int-text-const.pdf yields no results. What section is your "protection of the innocent" quote from?
    – Murphy
    Commented Aug 20, 2015 at 10:42
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    @Murphy: No, that is rather an implicit statement; I would put more weight on the statements from item V, which says that the burden of proof is with the prosecution (in a pure guilty-unless-proven-innocent system (let's call it "GUPI"), no proof would be required for establishing guilt), and item VIII, which says that the judge will only convict the accused if the judge is convinced that the accused is guilty (in a GUPI system, that statement would be nonsensical, as the accused would be guilty by definition - nothing that would require any convincing). Commented Aug 20, 2015 at 11:32

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