The decriminalization of adultery in Mexico—that is, the elimination of criminal penalties for spousal infidelity—has ignited a profound debate regarding its legal, social, and economic ramifications. This analysis explores the historical evolution of Mexican legislation concerning adultery, the key actors and arguments that propelled its decriminalization, and the adverse consequences this legal shift has had on the state, marriage as a civil contract, and society at large. Furthermore, it provides a comparative look at the United States and Spain, two jurisdictions with distinct approaches to marital infidelity, and considers whether there are any movements toward recriminalization in those nations. Finally, it puts forth a legislative proposal to reclassify adultery as “marital fraud,” a crime to be prosecuted ex officio. This proposal aims to remedy legal voids by incorporating modern evidentiary tools such as metadata, evidence of collusion, and harm to minors. The overarching goal is to equip the Mexican legal framework with effective mechanisms to safeguard the good faith inherent in the marriage contract, penalize deliberate deception, and mitigate the impact of such conduct on families and societal institutions.
Historical Context of Adultery Legislation in Mexico
Adultery has long been considered an illicit act in Mexico, a legacy of colonial and 19th-century criminal law. From the earliest Mexican penal codes, spousal infidelity was defined as a crime, typically prosecuted at the request of the wronged spouse. Early laws exhibited a clear gender bias, with female adultery punished more severely than male adultery, reflecting a patriarchal logic aimed at protecting male “honor” and ensuring paternity. For instance, the 1871 Penal Code of the Federal District mandated up to two years of imprisonment for a single man who engaged in sexual relations with a married woman (and for the adulterous married woman herself). However, a married man’s affair with a single woman carried lesser penalties and required the woman to be married for him to be considered a delinquent. Similarly, the 1832 Penal Code of Jalisco classified adultery as a “crime of impurity” that could only be prosecuted upon the husband’s accusation, with penalties including the banishment of the male adulterer and the confinement of the adulteress in a convent at the husband’s discretion. These statutes were products of an era where marriage was viewed in terms of property, and a wife’s fidelity was stringently policed through criminal law.
Throughout the 20th century, Mexican laws continued to criminalize adultery, albeit with moderated evidentiary requirements and penalties. Most legal codes required the infidelity to occur “in the marital home or with public scandal” to constitute a crime, indicating that the law was more concerned with punishing public affronts to family honor than private infidelity. The standard penalty, which remained in effect until recently, was up to two years in prison and a suspension of civil rights for up to six years for those found guilty under these aggravated circumstances. It was consistently treated as a private complaint; prosecution could only be initiated by the offended spouse against one of the parties—the unfaithful spouse or their lover—though technically both could be prosecuted if identified. The concept of spousal pardon also existed: if the wronged party forgave the unfaithful one, the criminal action would be terminated or the sentence nullified. Concurrently, adultery served for decades as a legal ground for a fault-based divorce in the civil codes of the states, allowing the innocent spouse to dissolve the marriage on these grounds.
Towards the end of the 20th century, in line with international trends to decriminalize private moral conduct, several states began to soften or eliminate the crime of adultery. By 2011, most states had repealed adultery from their local penal codes, viewing it as an outdated concept inconsistent with principles of legal equality. However, at the federal level, spousal infidelity remained a crime until that year. This changed in 2011 when the Congress of the Union, after a multi-year legislative process, finally removed the offense from the Federal Penal Code.[1]
The Decriminalization Process (2008–2011)
The formal process of federal decriminalization began in April 2008, when then-congressman Jorge Kahwagi of the Green Ecologist Party introduced a bill in the Chamber of Deputies to repeal the crime of adultery from the Federal Penal Code. The proposal was approved by the lower house and sent to the Senate, where it languished in committee for nearly three years. Finally, in March 2011, the Senate debated and approved the repeal of Chapter IV, Title Fifteenth, Second Book of the Federal Penal Code, removing all references to adultery as a crime. The reform passed with 69 votes in favor, 0 against, and 1 abstention, demonstrating an unusual political consensus on a criminal matter.
The primary arguments for eliminating the criminal offense were that adultery:
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“Causes no danger or harm to the offended spouse or society,” being a matter of private morality. Since it does not directly harm high-ranking collective legal interests, criminal punishment was deemed disproportionate.
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Was practically impossible to prove in court (given the requirement of being caught in the act or causing a public scandal), rendering it legally useless. Statistics supported this claim: in many states, complaints of adultery were rare and prosecutions minimal (for example, Jalisco recorded only 11 preliminary investigations in 2010 and 31 in 2011, with very few cases proceeding to trial each year).
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Was rooted in sexist values and the control of women. Legislators like Senator Pablo Gómez (PRD) described adultery as “an opprobrious crime constructed against women,” originating from 19th-century laws created by men to preserve the notion of women as male property.[2] The historical asymmetry was highlighted: the wronged husband’s violent reaction (crimes of passion) was often excused or mitigated, while male infidelity was culturally tolerated, making the criminal statute incompatible with gender equality.
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Was ultimately a matter of individual and mutual morality between spouses, not something the state should regulate through criminal law. In the words of the legislative opinion, the criminalization of adultery sought to protect concepts like “good name and prestige,” which are related to personal morality and dignity—extralegal goods the state is not obligated to protect through punishment. Then-Supreme Court Justice Arturo Zaldívar was quoted as saying, “fidelity is a matter for two,” emphasizing that the acceptance of infidelity falls within the private domain of the couple, not criminal law.
Based on these considerations, the reform was enacted in June 2011. Mexico thus joined the majority of Western nations that have decriminalized adultery in recent decades, viewing it as a private matter. Following the federal repeal, the few states that still criminalized adultery have gradually eliminated it. By 2014, at least 23 states had abolished criminal penalties for adultery, and today no state actively prosecutes it. In essence, since 2011, adultery in Mexico has been relegated to the civil sphere, primarily as a potential ground for divorce in states that still recognize fault-based divorce alongside the now-universal no-fault option.[3] It also persists in some special civil provisions, albeit with little practical effect, as will be discussed next.
Lingering Legal Traces and Regulatory Voids
Despite its decriminalization, the term “adultery” has not vanished entirely from the Mexican legal landscape. A notable example is Article 1316 of the Federal Civil Code, which still imposes a civil penalty: “A spouse who has been declared an adulterer by a court judgment shall be incapable of inheriting from the innocent spouse.” It also renders the adulterous spouse’s accomplice (the lover) incapable of inheriting. In practice, however, this provision has become a dead letter. Since 2011, without a crime of adultery or a corresponding criminal conviction, it is nearly impossible to obtain a “judgment” declaring adultery that would trigger this inheritance ban. Barring an attempt to establish such conduct through a civil action (which is not explicitly provided for), this clause is unenforceable—a clear legal gap resulting from an incomplete penal reform. Legal scholars have noted that since decriminalization, “it would be difficult to comply with section III (of art. 1316), unless another type of trial exists where this conduct is proven and condemned,” highlighting a regulatory inconsistency.
Similarly, while several state civil codes retain adultery as a ground for fault-based divorce, this has lost practical significance with the widespread adoption of no-fault or unilateral divorce. Today, even in states that list specific causes for divorce (including adultery), a spouse seeking to end the marriage can simply opt for the no-fault path without having to prove infidelity. This has simplified proceedings but also means that infidelity no longer carries automatic legal consequences in the dissolution of the marriage, beyond serving as a narrative of events in some cases.[4]
In conclusion, Mexico transitioned in 2011 from penalizing adultery to offering no direct legal sanction for the conduct, leaving redress to the moral, social, or private spheres (divorce, separation). This shift, though celebrated at the time for its progressive nature, has led to a range of negative outcomes, as discussed below: marital fraud facilitated by a lack of sanctions, unfair legal tactics in divorces, financial and familial harm, and a sense of legal vulnerability in the face of an act that remains a source of severe conflict for many couples.
Legal, Social, and Economic Consequences of Decriminalization
The elimination of criminal penalties for adultery in Mexico was explicitly intended to remove the state from the marital bedroom and promote gender equality. However, more than a decade later, it is possible to identify adverse effects that this regulatory change has had on various spheres:
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Facilitation of Marital Fraud and Collusion for Dispossession: With no criminal consequences, some unfaithful spouses act with greater impunity and premeditation to gain undue advantages. In some cases, adultery is not a spontaneous “lapse” but the beginning of a calculated strategy to defraud the innocent spouse. Decriminalization, combined with the ability to divorce without cause, can be exploited by the disloyal spouse to conspire with their lover to drain accounts, hide assets, or build a favorable legal case. This creates schemes of collusion where the lover acts as a third-party accomplice who infiltrates the family to corrode it from within. Such schemes can involve fraud, breach of trust, manipulation of children, and even corruption of judicial processes to the detriment of the wronged spouse. The lack of a specific criminal offense leaves such conduct to be addressed by general statutes (generic fraud, procedural fraud, etc.), which are difficult to apply. In short, planned infidelity is used as a means to defraud, turning what was once a “marital conflict” into a form of structured, yet unrecognized, family crime.
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Simulation of Bonds and Legal Deception: Decriminalization has also enabled unfaithful spouses to feign a good-faith continuation of the marriage while concealing its de facto breakdown in order to obtain benefits. This legal simulation can manifest in actions such as continuing to use joint assets as if nothing were amiss while diverting funds to the new relationship, inducing the other spouse to sign unfavorable agreements without disclosing the infidelity, or even misrepresenting the situation to family authorities (mediators, judges) by concealing the existence of a third party. All of this vitiates the consent and good faith that should govern the legal acts of the marital partnership. For instance, if a wife is living with her lover and still sues for alimony alleging abandonment, she would be committing procedural fraud (deceiving the judge about the real situation) and unduly exploiting the family legal framework with the covert intention of dispossession. Currently, such behaviors could only be prosecuted under offenses like simulation of legal acts or procedural fraud (Art. 311 of the Federal Penal Code)—existing crimes not designed for the family context. Consequently, many of these deceptions go unpunished or are not even reported, being dismissed as “divorce matters” rather than crimes.
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Patrimonial and Economic Impact: Unpunished infidelity can have severe effects on the family’s assets. The adulterous spouse, facing no sanction, may feel free to use common financial resources to sustain their extramarital relationship, leading to the dissipation of the patrimony. Expenses on hotels, gifts, and financial support for the lover diminish the assets of the marital partnership or the family, harming the innocent spouse and children. Although in a divorce proceeding it is possible to allege dissipation of assets to adjust the division, in practice, the division is often 50/50 in no-fault divorces. Thus, a deceived husband or wife may end up indirectly financing their partner’s affair without legal repercussions. Worse, there are cases where the unfaithful partner hides assets or transfers property to their lover’s name before the divorce, constituting a fraud that is difficult to prove without a specific law penalizing this patrimonial conspiracy. A recent journalistic analysis in Spain pointed out that “having a lover pays off: a divorce costs 3.6 times more than an affair”; many economically pragmatic unfaithful individuals prefer to remain married for the financial advantages while maintaining extramarital relationships. In fact, it is estimated that 30% of marriages that do not end in separation do so for financial reasons, which implies that in many households, tolerated (or secret) infidelity functions as a “solution” to avoid a costly divorce. This leaves the faithful spouse in a vulnerable position: trapped in a facade of a marriage that the other violates in practice, suffering an economic loss without clear legal tools for redress (since compensation for moral damages for infidelity, for example, is not granted in most jurisdictions). In contrast, other countries have indirect legal mechanisms: in the United States, for example, some states still allow for the denial of alimony or a reduction in the division of assets for the unfaithful spouse due to their misconduct, so proven infidelity has financial consequences. In Mexico, with the current no-fault divorce scheme, none of these consequences apply automatically, which can incentivize opportunistic behavior.[5]
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Impact on Child Custody and Well-being: The lack of legal censure for adultery has also had implications in the family sphere involving children. While, in principle, the private lives of parents should not affect custody arrangements, in reality, marital infidelity often creates high-conflict emotional environments that impact minors. Psychological studies indicate that parental infidelity is experienced by children as a traumatic situation that threatens family stability and can affect their emotional development. When children are involved or witness the deception—for example, if a parent leaves with a lover and the children perceive it—they may develop confusion, insecurity, feelings of abandonment, poor school performance, and even future patterns of mistrust in relationships. The National Institute of Mental Health of Peru warns that many children react with anger, fear, guilt, or shame to parental infidelity, especially if they are caught in the middle of the conflict or are instrumentalized by the unfaithful spouse to justify their behavior. In Mexico, since adultery is not an illicit act, there is no formal recognition of this collateral damage in family proceedings. For example, a spouse may have committed flagrant adultery but still request shared custody or extensive visitation, and the judge will only evaluate current parental capacity, without considering the betrayal or the psychological impact their behavior had on the children (unless it translates into directly harmful behavior towards them). In some cases, the lover even cohabits with the children before the divorce is finalized, which can lead to covert parental alienation or profound confusion in the minors. Currently, concepts like parental alienation or vicarious violence are being discussed in the law (e.g., recent reforms to protect minors from being manipulated in divorces), but they do not specifically address the situation of a third party furtively introduced into the family nucleus. The decriminalization of adultery, without accompanying safeguards in the family sphere, has left children without express recognition as indirect victims of this conduct. Certainly, the argument is not to criminalize infidelity for moral reasons alone, but ignoring its effects on children represents a gap in family protection policies. A comprehensive reform should consider psychological evaluations in cases of proven infidelity to determine if there was cognitive or emotional harm to the children, and if so, consider that factor in custody decisions or possible reparations.
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Institutional Burdens for the State: Paradoxically, although it was argued that the state should not expend resources on prosecuting adultery, its absolute decriminalization may be creating other institutional burdens indirectly. On one hand, the number of divorces in Mexico has increased significantly in recent years (partly due to no-fault divorce and sociocultural changes). While the decriminalization of adultery alone did not cause an immediate statistical rise in divorces, the social normalization of infidelity as a “private matter without consequences” may contribute to long-term marital instability. Broken or dysfunctional families often require greater state attention: more prolonged custody battles, social work interventions, financial support for single mothers/fathers, psychological assistance for affected minors, etc. In fact, some jurists who opposed the reform warned that removing the criminal deterrent would “encourage the practice (of adultery) to the detriment of women and families,” increasing family disintegration. Professor Jesús Morales of the University of Guadalajara, in 2014, called the proposal to eliminate adultery as a crime in Jalisco “misogynistic,” arguing that “we have a problem of family disintegration and (this) gives more weapons to machismo… you are giving an opportunity to disintegrate more (families), giving more to the depraved, polygamous, bigamous.” While his position may be considered conservative, it highlights a possible consequence: without sanction, the unfaithful spouse has no legal incentive to restrain their conduct, which could lead to more infidelity and breakups. Each contentious divorce implies costs for the administration of justice and potential subsequent conflicts (alimony lawsuits, domestic violence if the matter escalates, etc.). On the other hand, the lack of criminal sanction may lead some desperate wronged spouses to take justice into their own hands, generating violence. The legal literature prior to 2011 pointed out that the legal vacuum created by decriminalization “generates a serious void… homicidal behaviors executed by the offended spouse could be generated, upon seeing the impossibility of legally sanctioning the adulterers.” That is, there is a risk that in the face of legal impotence, so-called crimes of passion or violent aggressions may increase, which certainly burdens the criminal system in other, more serious areas. Although this effect is difficult to quantify, it should not be ignored in a criminal policy analysis.
In summary, the decriminalization of adultery in Mexico, while eliminating an anachronistic figure, was not accompanied by sufficient civil, criminal, or procedural measures to fill the void it left. The sanction was suppressed without creating alternatives to address situations of malicious deception, internal fraud, or family harm that can result from infidelity. The idea that infidelity is a “private matter without public consequences” has proven to be partially false: in practice, there are social consequences (family disintegration), economic consequences (depleted assets, costly litigation), and even institutional consequences (increased burden on civil courts, need for social assistance) that transcend the merely intimate. This leads us to consider international experiences that, although largely aligned with decriminalization, offer nuances on how to legally deal with adultery and its effects.
A Comparative Look: The United States and Spain
It is illustrative to briefly examine how two Western countries handle the issue of adultery, as they share civil or common law principles with Mexico but with particular developments: the United States, where some legal vestiges of sanctioning infidelity still exist in certain states, and Spain, where adultery was decriminalized in 1978 but new debates are emerging in light of family transformations.
In the United States, adultery is not actively prosecuted as a crime in the vast majority of states, and it has never been a federal offense.[1] However, surprisingly, several states still retain old laws against adultery in their penal codes (usually considered misdemeanors or minor offenses).[6] Until recently, states like New York technically kept the crime of adultery on the books (a class B misdemeanor), although it was not enforced in practice; in fact, New York repealed its century-old law in 2023 for being obsolete.[7] Other states—mainly conservative ones—still have it criminalized (Massachusetts, Michigan, South Carolina, among others), but its application is extremely rare. More relevant are the civil mechanisms that some states offer to the spouse harmed by infidelity:
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“Homewrecker” Lawsuits (Alienation of Affection): In six states (e.g., North Carolina, Hawaii, Mississippi, New Mexico, South Dakota, and Utah), civil actions known as “alienation of affection” and “criminal conversation” exist. These allow a deceived spouse to sue their partner’s lover for interfering in the marital relationship or for the act of having sexual relations with their spouse. These are remnants of common law that view marriage as having legal protection against external interference. While abolished in most of the country, in states like North Carolina, these lawsuits are still active, with about 200 cases of alienation of affection filed each year. The damages can be substantial: in 2018, a man won a verdict of $8.8 million against his wife’s lover after proving that he caused the breakdown of a marriage that was previously considered stable. To succeed, the plaintiff must “put the marriage on trial,” demonstrating that they had a happy relationship with genuine affection and that the third party’s interference caused its collapse. Although these cases may be seen as legal curiosities, they serve a function: recognizing a real harm to the innocent spouse and providing financial compensation, something non-existent in Mexico today. They also act as a deterrent (at least locally) against third parties attempting to start relationships with married individuals.
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Influence of Infidelity in Divorces (“Fault” States): The United States has had no-fault divorce nationwide for decades, but several states retain the option of alleging “fault” in divorces, including adultery, primarily to influence financial terms.[4] Approximately 22 states still allow adulterous conduct to be considered in deciding alimony and property division. For example, North Carolina law denies alimony to a dependent spouse who has committed adultery (and conversely, ensures alimony for the victim if the adulterer was the provider). Other states are not as strict but do empower the judge to adjust the distribution of property or maintenance obligations based on proven infidelity.[5] Thus, although there is no criminal punishment, there is an adverse financial consequence for the unfaithful: losing economic rights they would otherwise have. In contrast, Spain (and Mexico after the reform) follows the line that infidelity is irrelevant for dividing assets or pensions, which, in the opinion of some analysts, can lead to unjust situations (e.g., an adulterous husband receiving alimony from the wife he cheated on, if she had a higher income). In sum, the American model offers certain civil remedies that, without criminalizing the conduct, recognize adultery as a serious breach of the marital contract with legal effects.
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Military Code: It is worth mentioning that, apart from civil law, under the U.S. Uniform Code of Military Justice (UCMJ), adultery (redefined in 2019 as “extra-marital sexual conduct”) can be punished with severe disciplinary sanctions within the Armed Forces, as it is considered behavior prejudicial to good order and discipline. This reflects that, even in a liberal country, infidelity is recognized as legally relevant in certain contexts.
In general, the trend in the United States has been towards non-direct criminal intervention, but retaining certain legal “escape valves” for those harmed by adultery (either by suing the third party or influencing divorce settlements). There are no serious proposals to “re-criminalize” adultery at a general level; rather, the few states that still have such a law tend to repeal it due to disuse (as happened in New York). However, the aforementioned civil figures show a possible middle ground: without imprisoning the unfaithful, adultery can be treated as a contractual breach that entails civil liability. This idea connects with the reform proposal that will be presented later.
Spain offers an interesting case due to its contrasts and parallels with Mexico. Adultery was a crime in the Spanish Penal Code until 1978, with a marked discriminatory bias: the old wording mainly punished “the married woman who lies with a man who is not her husband, and he who lies with her,” while to penalize the adulterous husband, the condition of amancebamiento (having a concubine at home, or notorious relationships) was required. With the advent of democracy, Law 22/1978 of May 26 eliminated the crimes of adultery and amancebamiento from the Penal Code, considering them incompatible with the new constitutional framework of equality and the right to privacy. Since then, Spain has not considered adultery a criminal offense.
In the civil sphere, Spain went a step further than Mexico in marital liberalization: it legalized divorce in 1981 (non-existent during the Franco regime) and, after successive reforms, introduced the so-called “express divorce” in 2005, eliminating the requirement of cause and allowing divorce without alleging reasons after only three months of marriage. Therefore, today, infidelity is not sanctioned in either civil or criminal law. The duty of fidelity is still mentioned in the Spanish Civil Code as a marital obligation, but it lacks coercive mechanisms: the Spanish Supreme Court has reiterated in multiple rulings that spousal infidelity by itself does not give rise to compensation for moral damages, since the intended legal consequence is divorce and there can be no “double sanction.” Only in exceptional circumstances has civil liability been recognized, e.g., when there was concurrent serious deception—a landmark case was the compensation of €30,000 to a man whose wife concealed for 18 years that their daughter was not biologically his. In such situations, it is considered that the harm transcends common infidelity and constitutes a specific injury (deception in paternity). Outside of these cases, Spanish jurisprudence is clear in denying compensation to the victim of adultery, however painful, under the logic that the state does not enter into that private morality.
Regarding proposals for “reversal” or a return to punishing adultery in Spain, there have been no relevant initiatives in recent decades. The social and political consensus is that criminalizing it would be a regression incompatible with individual freedoms. Instead, Spain faces different modern challenges: the rise of new relationship models (polyamory, open relationships) is raising questions about the need to regulate multi-partner affective unions or fidelity in unconventional pacts. Spanish doctrine suggests that in the future there may be legislative adjustments to recognize rights or obligations in polyamorous relationships, but not to resurrect anachronisms.
However, a noteworthy emerging debate in Spain and other countries is “vicarious violence,” generally understood as violence (almost always by men) against children or the mother-child bond to cause harm to the woman. This concept has gained legal force (Spain criminalized vicarious violence in 2021 as part of gender-based violence). Why is this relevant here? Because just as this specific form of family harm was recognized, one could reflect on other forms of non-physical family violence or abuse. Some analysts in Mexico have pointed out that what could be called “juridical-family violence through premeditated infidelity” is a real phenomenon: that is, using the family structure and laws covertly to harm the spouse (through adultery, manipulation of children, and malicious litigation). This figure is not criminalized in any country, but the Mexican proposal to be presented points in that direction. In Spain, something similar is not yet being discussed; however, as our countries share a concern for protecting children and preventing legal abuse in divorces, there might be academic receptivity to analyzing these gaps.
In summary, Spain decriminalized adultery more than 45 years ago and shows no intention of reversing it; it relies on private solutions (divorce) and cultural evolution (greater tolerance for non-monogamous arrangements) to deal with infidelity. The United States, on the other hand, also does not criminally prosecute these behaviors except in very specific situations (military, lagging states), but it does provide civil remedies that recognize adultery as a wrong against the innocent spouse. This comparison suggests that the dilemma is not solely between penalizing with prison or completely ignoring: there are intermediate figures (civil, administrative) that can be implemented.
Taking into account the lessons learned and the failures observed after decriminalization in Mexico, a proposal for a comprehensive legal reform is presented below. This proposal seeks to reintroduce adultery into the Mexican legal framework, not from the traditional moralistic perspective, but as a form of fraud against the marital contract and the family, which merits proportionate legal consequences and effective protection for the victims.
A Proposal for Legal Reform: Adultery as Ex Officio Marital Fraud
Central Objective of the Reform: To incorporate into Mexican legislation a legal concept that sanctions marital infidelity when it involves a bad-faith violation of the marriage contract with intent and collusion, causing financial, familial, or emotional harm to the innocent spouse. It is proposed to criminalize “marital fraud” or “spousal fraud” as a crime prosecuted ex officio, which would fill the gap between the purely civil and criminal spheres, recognizing the seriousness of certain premeditated infidelities. This is not about criminalizing private sexual conduct itself, but about punishing deception and abuse of trust committed under the guise of marriage.
The main pillars of the reform would be:
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Criminalization of Marital Fraud: Create an autonomous crime in the Federal Penal Code (and recommend its adoption in state codes) that is established when a spouse, “with the intent of illicit gain or undue benefit and in violation of marital good faith,” engages in acts of infidelity accompanied by substantial deception and concealment from their partner, resulting in financial, familial, or moral damage. In essence, it adapts the general concept of fraud (obtaining an advantage through deceit) to the special context of marriage, which is a contract based on trust. This criminal offense would consider the unfaithful spouse as the primary active subject, and could include the third-party lover as a co-perpetrator or participant when they consciously collaborate in the plan of deceit and dispossession. Ex officio prosecution is justified because the protected legal interest is not sexual morality, but public faith in the institution of marriage as a contract and the rights of the spouse and family affected by the fraud. By being ex officio, it avoids the need for the victim to initiate criminal action (which often does not happen due to blackmail, economic dependence, or manipulation), and sends a clear message of social reproach for these behaviors.
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Objective Elements and Evidence (including Metadata): The reform would clearly define the elements that constitute the crime to avoid ambiguities that could lead to prosecutions for simple casual infidelity. It would be necessary to prove:
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A concurrent extramarital relationship of the accused, through solid evidence (messages, photos, videos, geolocation, etc.). The use of metadata and digital evidence—now abundant in infidelity cases (e.g., chat histories, GPS locations, call logs)—would be admissible, ensuring its lawful acquisition. These data could corroborate the existence and duration of the hidden relationship.
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Premeditated intent and concealment: Infidelity alone would not be sufficient; it would have to be demonstrated that the unfaithful spouse actively hid the relationship and deceived their partner with the purpose of obtaining some benefit or advancing a plan (e.g., transferring assets without the other’s suspicion, buying time to prepare an advantageous lawsuit, etc.). Collusion between the unfaithful spouse and their lover would be an aggravating factor: e.g., if it is proven that both coordinated actions (messages revealing a plan to make the spouse give up the house, etc.). Here, proof of collusion could be derived from legally intercepted communications or testimony from third parties who observed the conspiracy.
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Concrete harm caused to the innocent spouse or the family. This harm could be financial (disposition of resources, hidden debt, spending of common money on the illicit relationship), familial (neglect of duties towards children, introducing the lover into the home causing public humiliation), or personal (emotional or moral damage comparable to civil moral damages, but recognized in the criminal sphere as a consequence). In the case of minor children, the cognitive/emotional harm to them would also be assessed as part of the prejudice. Expert psychological reports could certify whether the minors suffered emotional disorders as a result of the environment created by the infidelity—for example, anxiety, depression, or academic decline.
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Causal link: that is, that the deliberate deception was the cause of the harm. For example, that the accused induced the spouse to sign an agreement or make a financial disposition by taking advantage of their ignorance of the infidelity (vitiated consent), or that their prolonged concealment aggravated the damage.
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Exclusion Clause for “Private Cases”: To avoid criminalizing situations of mere marital failure without fraudulent intent, the law could include a provision that excludes circumstantial infidelities without profit or tangible harm from this crime. That is, to differentiate adultery-fraud (with malice and gain) from purely emotional or passionate infidelity which, however morally reprehensible, did not seek to defraud the spouse. Only those cases where a pattern of malicious and damaging behavior is proven would be prosecuted. This would preserve the private sphere to some extent and prevent the criminal system from being flooded with trivial or vengeful infidelity complaints.
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Sanctions and Consequences: Given the proposed criminal nature (fraud against the family), the penalties could be moderate but with restorative components:
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Imprisonment: for example, 1 to 5 years in prison (placing it in a range similar to generic fraud, which in the Federal Penal Code Art. 386 is punishable by 3 days to 12 years depending on the amount, although here the damage is not only economic). The specific range would be determined by calibrating the typical severity of these cases. In many instances, alternative resolutions (conditional suspension, restorative agreements) could be possible if the victim desires, but the existence of the penalty reinforces its deterrent nature.
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Fine or reparation of damages: payment of damages to the wronged spouse would be imposed. This would include the restitution of fraudulently diverted assets or money, compensation for moral/familial damage (prudently quantified, similar to civil indemnities), and payment for psychological therapy for the victim and children if emotional impact is demonstrated. Basically, transferring the possibility of comprehensive redress for the affected party to the criminal sphere.
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Loss of legal benefits: the offending spouse, upon being convicted of marital fraud, should lose certain civil rights regarding the dissolved marriage. For example, automatically losing any right to alimony from the innocent party (if they had one), losing parental rights or custody of the children if it is proven that their actions harmed them (at least temporarily or under supervision, according to professional evaluations), and being declared incapable of inheriting from the ex-spouse, thus giving real effect to the aforementioned Art. 1316 of the Federal Civil Code, which is currently a dead letter. These civil consequences can be integrated via reforms to the Civil Code: adding conviction for this crime as a cause of succession indignity, and establishing that it constitutes per se a serious injury for the purposes of parental authority. In this way, the sanction is not only to punish but to restore equity: whoever betrayed in such a way should not subsequently benefit from their spouse in any sense.
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Ineligibility to contract a new marriage with the lover for a certain time: This measure existed in some old codes (e.g., after adultery, a prohibition on the adulterers marrying each other for a period). It could be revived symbolically or in reality, to avoid the situation—somewhat common—where the fraud is consummated, the adulterer gets a divorce, and then legitimizes the union with their accomplice. While this may sound like an intrusion into individual freedom, it has a contractual logic: it is similar to prohibiting someone from benefiting from their own fraud. However, this sub-measure would be optional and likely controversial in terms of human rights, so its constitutional viability would have to be thoroughly analyzed.
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Procedure and Specialized Investigation: Ex officio prosecution would allow the Public Prosecutor’s Office to initiate an investigation upon learning of the possible commission of these acts (through a complaint from the victim, a family member, or even from evidence that arises in a civil trial). It is suggested to create specialized protocols for these crimes given their sensitivity: units with personnel trained in family mediation, forensic accounting (to trace assets), and cybercrime (for handling digital evidence of infidelity). A conciliation/restoration phase could be implemented before judicialization, offering the offender the possibility of fully repairing the damage (economic and emotional) to their family in exchange for a reduced sentence. But if there is no cooperation, criminal action would be taken as in any fraud case. Likewise, this criminal path would have to be harmonized with parallel divorce proceedings: for example, by establishing that the existence of an investigation for marital fraud temporarily suspends the civil divorce procedure or its financial effects, to prevent the guilty party from rushing to divorce and dispose of assets before the criminal sentence. Similarly, if in the family trial, malicious infidelity is determined, that evidence should be transferred to the criminal case and vice versa, promoting cooperation between family and criminal courts (perhaps via judges specialized in both matters for these cases).
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Use of Technological Tools (Metadata): Given the historical difficulty of “catching them in the act” of adultery (as the criticism of the old criminal type mentioned), the reform recognizes that today the digital trail reveals most infidelities. It will be proposed to reform the legislation on digital evidence and telecommunications so that, in the face of a well-founded suspicion of marital fraud, a judge can authorize the obtaining of metadata: cell phone geolocation, cross-referencing of calls, forensic copying of electronic messages, etc. Always respecting fundamental rights (a judicial order would be required), but facilitating proof of the duration and intensity of the extramarital relationship and any conspiracy (e.g., emails planning how to litigate against the spouse, messages coordinating the emptying of accounts, etc.). This would modernize the investigation, overcoming the outdated requirement of seeing the adulterers “in bed.” Additionally, the use of domestic surveillance cameras or environmental recordings—now common—could be integrated, provided they are obtained legally, to prove the lover’s visits to the marital home or other relevant facts.
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Prevention and Non-Penal Components: Alongside the creation of this criminal offense, the reform should include preventive and educational aspects. For example:
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Optional contractual fidelity clauses: explicitly allowing couples, upon marrying, to agree on clauses with civil consequences in case of infidelity (unequal division of assets, waiver of alimony, etc.). Some already do this via prenuptial agreements, but it is worth promoting it as contractual self-protection, which could deter fraud.
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Awareness campaigns: disseminating that infidelity with deceit is a form of financial and psychological violence, not a harmless game. It would communicate that it now has legal repercussions. This would align social perception with the desired legal reality.
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Counseling and support for victims: often the deceived spouse takes time to realize or act. The reform could contemplate free legal counseling units where they are informed of their rights, helped to gather evidence (e.g., preserving messages), and provided with emotional support so they can take legal action with strength.
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Constitutional Foundation and Feasibility: It is foreseeable that such a proposal will generate discussion about the invasion of marital privacy. However, it is defensible under the argument that the state can indeed intervene when the legal order and public faith are violated by fraudulent practices, even within the family. By criminalizing it as fraud, it is not moralizing sexuality, but protecting the legitimate trust placed in the marriage contract. The Supreme Court of Justice has held that civil contracts can be annulled due to fraudulent intent or bad faith; extending that notion to the criminal sphere when there are extraordinary fraudulent behaviors would be coherent. Furthermore, the reform aims to equalize protection for both sexes: historically, criminal adultery was biased, but this marital fraud would apply equally to unfaithful husbands or wives, and even recognizes the possibility of lovers of any gender (including homosexual relationships hidden under a heterosexual marriage, as there is also deceit there). This aligns it with principles of equality and non-discrimination.
Political feasibility could be supported by statistics and research: for example, surveys could reveal what percentage of contentious divorces involved infidelity and economic fraud. Hard data, such as “7 out of 10 marriages separate” in Spain or high divorce rates in Mexico (INEGI reported an increase in the divorce/marriage ratio in the last decade), suggest that many marriages fail, and within those breakups, infidelity remains a significant cause. Showing how the absence of legal consequences has allowed for abuse would help to gather support. International doctrine can also be cited: for example, the United Nations has called on countries to decriminalize adultery because it is applied against women, but our proposal does not contradict that spirit, as it does not seek to return to moralistic punishment but to create a gender-neutral crime of a financial-familial nature.
Finally, this reform will require coordination between powers: legislative to approve it, judicial to train judges in its application (especially in obtaining digital evidence, assessing emotional damage), and executive for prosecutors to develop the aforementioned protocols. Current regulatory gaps—such as the dilemma of Art. 1316 of the Federal Civil Code regarding adulterous heirs—would be resolved by the existence of a (criminal) “trial” that could declare someone a fraudulent adulterer, thereby applying that succession limitation.
Conclusions
The decriminalization of adultery in Mexico, while responding to a laudable purpose of legal modernization, suffered from technical deficiencies and omissions that have resulted in palpable negative consequences for individuals and society. Historically, adultery transitioned from being a sexist crime to being considered an exclusively private matter; however, reality shows that certain forms of adultery constitute true fraud and assaults on trust that deserve a legal response. It has been established that:
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The current legal framework offers insufficient protection to the faithful spouse against premeditated deception and covert dispossession.
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The absence of sanctions may have incentivized opportunistic behaviors, leaving victims without adequate redress and even at risk of extralegal violence.
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Children and innocent third parties suffer the ravages of unpunished infidelity, with emotional costs that society eventually also pays (in the form of psychological care, minors with behavioral problems, etc.).
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There are regulatory gaps and inconsistencies (inoperative civil clauses, lack of specific criminalizations) that should be remedied to give coherence to the legal system.
The proposal to recognize malicious adultery as ex officio marital fraud represents a structural response to these problems. Far from restoring archaic visions, the initiative focuses on the protection of the marriage contract as the basis of the family and on the sanctioning of abuse of trust. In the international concert, it would be an innovative figure—few countries have conceptualized the issue from this perspective of fraud—but it could set a precedent, just as Mexico has been a vanguard in other family matters (e.g., express divorce in Latin America).
It is important to emphasize that this reform does not seek to meddle in the legitimate intimacy of individuals, nor to punish eventual mutual agreements of a couple (for example, consensual open marriages, which would naturally fall outside the proposed criminal type as there is no deceit). It focuses on situations in which one of the spouses unilaterally violates the foundations of the marital agreement surreptitiously and with undue advantage. In that sense, it reinforces the principle of contractual good faith and provides a legal tool for extreme cases that are currently unattended.
From the perspective of legislative impact, the reform would bring about:
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Benefits in the protection of the family and patrimony: it would reduce the impunity of behaviors that today dissolve fortunes and families in the shadow of the law. It would possibly have a deterrent effect on spouses who, in the face of a crime, would think twice before getting involved in fraud with their lover. This could translate into fewer frauds, and perhaps even fewer opportunistic infidelities.
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A moderate burden on the criminal system but relief for the civil system: It is true that a new criminal path would be opened that could add work for prosecutors and judges. However, many of these conflicts already exist but are unsatisfactorily aired only in civil family courts. By being criminalized, it is likely that several cases would be channeled early and resolved by agreements (given the criminal threat). In the long run, it could reduce contentious civil litigation, as the unfaithful spouse will know that it is not in their interest to get entangled in lawsuits—negotiation and fair play would be incentivized.
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Normative adequacy: Civil and criminal laws would be harmonized, covering gaps (inheritance, alimony, custody) based on the criminal figure. This gives consistency to the legal order: the message of the law would be that marriage is free to be entered into or dissolved, but not to be betrayed with malicious impunity.
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Possible criticisms and how to mitigate them: Undoubtedly, there will be voices arguing that this initiative “regresses” by criminalizing marital issues. They should be answered by emphasizing that the proposed crime is fraud and collusion to commit a crime, not extramarital sex per se. A temporality clause could also be set, evaluating the effectiveness of the law after, say, 5 years of its entry into force: did it prevent abuses? was it applied justly? were there successful conciliations? If necessary, it would be calibrated or repealed if it does not meet its objective. This pragmatic approach can reassure skeptics.
In conclusion, this investigation maintains that the absolute decriminalization of adultery left a void that has been exploited to the detriment of the family and equity. Recovering a legal action against fraudulent adultery—with a modern, equitable design oriented towards repairing the damage—would benefit the state (by strengthening the marital institution as the basis of society), loyal spouses (by providing them with justice), and children (by protecting them from environments of lies and abuse). Mexico can and should innovate in its family legal framework to close the door on simulation and unpunished deception. The proposal outlined here seeks precisely to initiate that path of reform, inviting jurists, academics, and legislators to dialogue to perfect it and make it a reality.
In plain words: fidelity may be a matter for two, but fraud is a matter for the law. Reincorporating an effective response to adultery when it becomes fraud into the legal system will be a step forward in the protection of Mexican families and in the vindication of marriage understood not as a moral cage, but as a contract of loyalty and honesty.
Sources consulted: The present proposal and analysis are based on a wide range of legal and doctrinal sources, including legislative debates from 2011, specialized journalistic articles, academic studies on adultery and family law, opinions of legal experts, as well as comparative data from foreign jurisdictions (e.g., cases of “alienation of affection” in the U.S. with million-dollar damages, and the Spanish experience with decriminalization since 1978). Available statistics on adultery complaints before its elimination (e.g., Jalisco 2007–2014) and on current behaviors surrounding divorce and infidelity (surveys in Spain showing economic motivations for not divorcing) have been incorporated. Likewise, psychological studies that show the negative impact of infidelity on minor children have been taken into account. All of this has been interwoven to solidly support the need for this legal reform in Mexico.
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