Mexico’s Congress of the Union, is the federal legislative body of the country. It consists of two chambers: the Senate of the Republic and the Chamber of Deputies.
For any international corporation operating in Mexico, a foundational understanding of the nation’s legal and regulatory landscape is a cornerstone of success. While the executive branch and its various ministries are the most visible points of daily interaction, the true source of all federal law lies within the Poder Legislativo, or the Legislative Power. This branch of government, embodied by the Congress of the Union, is the engine that creates, debates, amends, and ultimately passes the laws that govern every aspect of business in the country—from tax codes and labor rights to environmental standards and trade policy.
A common mistake for foreign executives is to underestimate the importance of the legislative process. The laws that dictate your company’s compliance obligations are not static. They are constantly evolving through a complex and deliberate process of political negotiation and legal procedure. Understanding this process is not merely an academic exercise. It is a critical component of strategic foresight. It allows a company to anticipate potential regulatory shifts. Also, it can understand the political forces that shape the business environment and engage in informed advocacy.
This definitive guide provides a comprehensive, in-depth analysis of Mexico’s legislative branch. It is designed specifically for business owners and general managers. We will explore the bicameral structure of the Congress, detail the specific powers and composition of both the Chamber of Deputies and the Senate, and provide a clear, step-by-step breakdown of the legislative journey from a simple proposal to its official publication as law. Ultimately, this guide will provide the clarity needed to understand the very source of the legal and regulatory landscape in Mexico.
The General Congress of the United Mexican States, is the legislative body of the federal government of Mexico. It consists of two chambers: the Senate of the Republic and the Chamber of Deputies. Its 628 members (128 senators and 500 deputies) meet in Mexico City.
| Type | Bicameral |
|---|---|
|
Founded |
1821 |
|
Total Senators |
128 |
|
Total Deputies |
500 |
To understand the structure and function of Mexico’s modern Congress, one must first appreciate the historical context from which it was born. The legislative framework is a direct product of the country’s struggle for democratic stability and a reaction against the concentration of power that defined much of its 19th and early 20th-century history. The Political Constitution of 1917, drafted in the aftermath of the Mexican Revolution, is the foundational document that establishes the structure and powers of the legislative branch.
The framers of the constitution were deeply influenced by two primary historical experiences: the instability of the 19th century and the authoritarianism of the Porfiriato dictatorship. Consequently, they designed a system intended to achieve two primary goals:
To prevent the rise of another dictator, the constitution established a strong separation of powers between the executive, legislative, and judicial branches. The Congress was envisioned as a powerful check on the authority of the President.
To balance the interests of a large and diverse country, the framers created a bicameral (two-chamber) legislature. This system was designed to provide representation based on both population (in the lower house) and geography through the individual states (in the upper house).
This constitutional framework, with its emphasis on checks and balances and dual representation, is the blueprint for the Congress of the Union that operates today. It created a deliberative body where national laws must pass through multiple stages of debate, negotiation, and approval before they can take effect.
The legislative power of the Mexican federal government is vested in the Congress of the Union. As established by the Constitution, the Congress is a bicameral legislature, meaning it is composed of two distinct and co-equal chambers:
The Chamber of Deputies (Cámara de Diputados): The lower house.
The Senate of the Republic (Cámara de Senadores): The upper house.
For a bill to become a federal law, it must be approved in its identical form by a majority vote in both chambers before it can be sent to the President for signature. This bicameral system ensures a more thorough and deliberative process, as legislation is scrutinized from two different representational perspectives. The Congress convenes in regular sessions twice a year, from September 1st to December 15th, and from February 1st to April 30th, though special sessions can be called. Let’s explore the specific composition and powers of each chamber.
The Chamber of Deputies is the lower house of the Congress and is designed to directly represent the citizens of Mexico based on population. It is a large and dynamic body that is often seen as being more closely connected to the immediate political pulse of the nation due to its shorter electoral cycle.
The Chamber of Deputies is composed of 500 members, known as diputados. These members are elected for a three-year term through a “parallel voting” system that combines two methods of election to ensure both direct representation and partisan fairness:
300 Deputies by Majority Vote: Three hundred deputies are elected directly from single-member districts, similar to the U.S. House of Representatives. Each state is divided into a number of federal electoral districts based on its population, and the candidate who wins the most votes in each district is elected. This ensures every region of the country has a directly accountable representative.
200 Deputies by Proportional Representation: The remaining two hundred deputies are elected through a system of proportional representation from five large, multi-state electoral regions. In this system, voters cast a vote for a political party, not an individual candidate. Each party presents a ranked list of candidates for each region. The 200 seats are then allocated to the parties based on the percentage of the national vote they receive. This system ensures that smaller political parties that have significant national support, but may not be able to win individual districts, can still gain representation in the Congress.
Following a significant political reform, deputies can now be re-elected for up to four consecutive terms (a total of 12 years).
While most legislation must pass through both houses, the Constitution grants the Chamber of Deputies several exclusive and highly important powers. The most significant of these is the power of the purse.
The Chamber of Deputies has the exclusive power to approve the annual Federal Expenditure Budget.Each year, the President, through the Ministry of Finance, submits a proposed budget. The Chamber of Deputies then debates, amends, and ultimately approves how all federal funds will be spent for the upcoming fiscal year. The Senate has no formal role in this process. This is arguably the most powerful check the legislature has on the executive branch, as it directly controls the financial resources of the entire government.
The Chamber is responsible for overseeing the Auditoría Superior de la Federación (ASF), which is the supreme audit institution of Mexico. The ASF is responsible for auditing the use of public funds by all federal entities.
The Chamber of Deputies acts as the prosecuting body in any impeachment proceedings against high-level public officials, including the President.
In the day-to-day legislative process, the Chamber of Deputies acts as a co-equal partner with the Senate. A bill can originate in either chamber, but it must be approved by both. Given its larger size and more diverse representation, debates in the Chamber can often be more contentious and politically charged than in the Senate.
The Senate of the Republic is the upper house of the Congress. It is designed to represent the interests of the 32 federal entities (31 states and Mexico City) that make up the Mexican federation. It is generally considered a more deliberative and stable body than the Chamber of Deputies, due to its longer term lengths and its role in foreign policy and high-level appointments.
The Senate is composed of 128 members, known as senadores. These members are elected for a six-year term, concurrent with the President of the Republic, through a mixed system that ensures representation for each state:
96 Senators by State-Level Vote: Each of the 32 federal entities elects three senators.
Two seats are awarded to the political party or coalition that wins the most votes within that state.
One seat is awarded to the political party that finishes in second place. This is known as the “first minority” senator and ensures that the second-largest political force in each state has representation in the Senate.
32 Senators by National Proportional Representation: The remaining thirty-two senators are elected from a single, national list based on the percentage of the national vote each political party receives. This provides an opportunity for parties to bring in national figures or experts who may not have a strong regional base.
Following recent reforms, senators can now be re-elected for one additional consecutive term (a total of 12 years).
The Constitution grants the Senate several exclusive and powerful responsibilities, primarily focused on foreign policy, high-level appointments, and matters of federal jurisdiction.
This is perhaps the Senate’s most important exclusive power. All international treaties and conventions negotiated by the President and the Ministry of Foreign Affairs must be ratified by a majority vote in the Senate before they can become legally binding for Mexico. This includes all of the free trade agreements that are so critical to the nation’s economy.
The Senate has the power to confirm many of the President’s most important appointments. This includes:
Ambassadors and Consuls General.
Justices of the Supreme Court of Justice of the Nation.
The Attorney General of the Republic.
The heads of the autonomous regulatory bodies for energy and telecommunications.
The Senate has the authority to analyze the President’s reports on national security, to authorize the movement of national troops outside of the country, and to act as a mediator in disputes that may arise between the different levels of government (federal, state, and municipal).
In the legislative process, the Senate acts as a crucial chamber of review. Any bill passed by the Chamber of Deputies must also be debated and approved by the Senate, and vice versa. Given its smaller size and longer terms, the Senate often provides a more measured and long-term perspective on national legislation. Its role in representing the states ensures that the interests of the federation are taken into account during the lawmaking process.
The commissions (comisiones) are the real working engines of the Congress. They are the specialized groups of expert legislators responsible for analyzing, debating, and modifying proposed laws before they reach the full floor for a vote. These people are the talent that does the heavy lifting.
Both the Chamber of Deputies and the Senate have their own set of commissions, which generally mirror the structure of the executive branch’s ministries. There are several types, but the most important are the Ordinary Commissions (Comisiones Ordinarias), which are permanent and handle the bulk of legislative work.
The Senate of the Republic is the upper house of the Congress. It is designed to represent the interests of the 32 federal entities (31 states and Mexico City) that make up the Mexican federation. It is generally considered a more deliberative and stable body than the Chamber of Deputies, due to its longer term lengths and its role in foreign policy and high-level appointments.
The process begins with a formal proposal for a new law or an amendment to an existing one. This is known as an iniciativa.
The Mexican Constitution grants the right to propose new federal laws to:
The President has the power to introduce bills directly to either chamber of Congress. Often, the most significant reforms of a presidential administration begin as an initiative from the executive branch.
Any member of the Chamber of Deputies or the Senate can propose a new law.
The legislatures of the 31 states and Mexico City have the right to propose federal laws.
A group of citizens representing at least 0.13% of the national electoral roll can also formally introduce a citizen’s initiative. Although this is very uncommon.
Once an initiative is introduced in one of the chambers (known as the Chamber of Origin), it is not immediately debated by the full house. Instead, it is referred to one or more specialized legislative commissions.
This is one of the most critical and often overlooked parts of the process. The commissions are the primary working groups of the Congress. They are composed of a smaller number of legislators from different political parties who have expertise in a particular subject area (e.g., finance, economy, labor, health). The commission is responsible for:
The commission conducts a detailed technical and legal analysis of the proposed bill.
It holds meetings to debate the merits of the proposal and can make significant amendments, additions, or deletions to the original text.
The commission may hold hearings and invite outside experts, academics, and representatives from the private sector to provide their opinions on the proposed law.
After its analysis, the commission votes on whether to approve the bill. If it is approved, the commission drafts a formal report, or dictamen, which includes the final, proposed version of the law. This dictamen is then sent to the full floor of the chamber. If the commission votes against the bill, it is effectively killed and does not proceed.
Once a bill is approved by its commission and a dictamen is issued, it moves to the full floor (el Pleno) of the Chamber of Origin for its formal debate.
The Reading: The dictamen is read before the full assembly of deputies or senators.
The Debate: Legislators from different political parties then have the opportunity to debate the bill, making arguments for or against its passage. Further amendments can be proposed from the floor during this stage.
The Vote: Finally, the bill is put to a vote. For most laws, a simple majority of the members present is required for approval. For constitutional amendments, a two-thirds majority of the members present is required.
If the bill is approved in the Chamber of Origin, it is not yet law. The entire approved text is then sent to the other house, which now acts as the Reviewing Chamber (Cámara Revisora).
The process then repeats itself. The bill is referred to the relevant commissions in the Reviewing Chamber for analysis. If approved by the commission, it moves to the full floor for debate and a final vote. The Reviewing Chamber has three options:
Approve the Bill without Changes: If the Reviewing Chamber approves the bill in its exact form, it is then sent to the President.
Reject the Bill Entirely: If the Reviewing Chamber rejects the bill, it is sent back to the Chamber of Origin and generally cannot be brought up again during that legislative session.
Amend the Bill: If the Reviewing Chamber makes any changes or amendments to the bill, it must be sent back to the Chamber of Origin. The Chamber of Origin then only debates and votes on the specific changes made by the Reviewing Chamber. This back-and-forth process continues until both chambers have approved the exact same text.
Once a bill has been approved in its identical form by both the Chamber of Deputies and the Senate, it is sent to the President of the Republic for their approval. The President has two options:
Promulgate the Law: If the President agrees with the new law, they sign it and order its publication.
Veto the Law: If the President disagrees with all or part of the bill, they have the power to veto it (derecho de veto). The President must return the bill to its Chamber of Origin with their observations within 30 days. The Congress can then override the presidential veto if the bill is once again passed by a two-thirds majority in both chambers. If the veto is overridden, the President is then obligated to publish the law.
The final step in the process is the publication of the new law in the Diario Oficial de la Federación (DOF), or the Official Gazette of the Federation. A law is not legally binding until it has been published in the DOF. The publication itself will specify the date on which the new law will enter into force.
The following is an exhaustive list of all Mexican Federal Laws. You can find these laws in Spanish on the Chamber of Deputies website.
At Start-Ops, we translate the most important business related Mexican Laws so our audience can follow up on our blog’s topics. You can find these translated laws in our resources section.
The legislative process in Mexico is a complex, deliberative, and multi-stage journey. For a foreign business, understanding this process is a matter of strategic importance. The laws that govern your operations are not created in a vacuum; they are the product of a dynamic system of political negotiation, technical analysis, and constitutional checks and balances.
By monitoring the initiatives that are being debated in the commissions and on the floors of the Congress, a company can anticipate potential regulatory changes that may impact its industry long before they become law. This provides invaluable time to adapt business strategies, plan for new compliance requirements, and engage in informed advocacy.
At Start-Ops, we provide our clients with the expert guidance necessary to understand and navigate this complex legal and political environment. We monitor legislative developments and help our clients understand the potential impact of new laws and regulations on their operations. We handle the complexity of the Mexican system so you can focus on your core business, confident that you are operating on a secure and compliant legal foundation.
Contact us for a strategic consultation to explore how we can help you navigate Mexico’s legislative and regulatory landscape with confidence.
