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What we now call Mexico - or, to give it its full name, the United Mexican States - was ruled by both the indigenous people and the Spanish conquerors in an authoritarian, hierarchical and centralised style which has had its impact on Mexican political institutions even today. Indeed, when the country first became independent in 1821, its first leader Agustín de Iturbide declared himself emperor. One infamous leader Porfirio Díaz managed to rule from 1884 to 1911.

As is the case with all nations, the constitution of Mexico reflects its history and the political system continues to evolve with current circumstances. However, given the turbulent history of the last 100 years and the present state of flux in domestic politics, this is especially true of Mexico.

Compared to the other nations of North America, Mexico is similar to the United States [click here] in having a presidential system with separation of the powers but different from Canada [click here] which has a parliamentary system based on the British model. What is most different about Mexico, compared to both the USA and Canada, is that it has low levels of transparency and accountability and high levels of corruption and criminality. But, as this essay will make clear, in recent years there has been real progress in democratic consolidation.


Mexico achieved its independence in 1821 and has had several constitutions since then. The most durable constitution after the present one was that of 1857 which lasted until 1917. Following the Mexican Revolution of 1913-1916 and a social constitutional convention, the present constitution was adopted in 1917.

It can be argued that one of the principles that emerged from the revolutionary era represented by the 1917 constitution is the notion of 'constitutionalism', that is a legitimacy of and support for the fundamental principles of the constitution which is reflected in the popular culture. A notable illustration of this us that, in many Mexican cities (including the national capital), squares, streets and other features are named after the constitution itself or after notable articles of the constitution.

Articles which are particularly highlighted in this way are Article 3 on education, Article 27 on ownership of land and water, Article 123 on labour rights, and Article 130 on church restrictions.

A key principle of the constitution - set out in Article 83 - is that leaders should only rule for one term of six years. This was a reaction to the Portifirio Díaz rule of seven consecutive terms totalling 27 years and reflected the slogan of the 1911 revolution "Effective Suffrage and No-Reelection".

On the one hand, this rule can be seen as beneficial in that it prevents the sort of long-term, one-person rule that we have seen in many African and Asian countries. On the other hand, if a leader will never have to face re-election, there is little personal incentive to rule in a manner which attracts popular support (although, of course, there remains an incentive to use his power in a manner which is likely to result in his successor coming from the same political party).

A further complication of the 'six year rule' is that constitutionally it was only intended to apply to the executive (that is, the President) and not the legislature (that is, the Chamber of Deputies). However, in 1934, the rule was applied to Deputies as well, although qualified by the word 'consecutive'. Above all, this change weakened the legislature in relation to the executive as it is means that Deputies can build up limited experience and authority and gives the executive power over the nominees for congressional seats.

Furthermore this rule has the perverse effect of making Deputies lacking in accountability, because they are not going to face re-election at the end of their term and possibly ever, and encouraging them to seek as much personal advantage as possible, since they are probably only going to have one opportunity to milk the system.

To make a change to the constitution requires the approval of both houses of the federal legislature and the approval of at least 17 of the 32 state legislatures. in fact, the Mexican constitution is the most amended in the world - more than 500 changes in just over 100 years.


The President of the United Mexican States - the proper name for Mexico - is the head of the state and the government, as well as the commander-in-chief of the Mexican military forces. The President appoints the Cabinet and other officers. The President is responsible for executing and enforcing the law, and has the power to veto bills. It is a powerful position.

The President is elected for six years and can only serve one term. However, although this arrangement prevents self-perpetuating individual leaders, it has not stopped a self-perpetuating political leadership through the agency of one party so, for 71 years (1929-2000), the country was ruled by a succession of presidents from the same semi-authoritarian political party, the Institutional Revolutionary Party (PRI).

The last 10 presidents have been as follows:

The last presidential election was held on 1 July 2018. The winner - on his third attempt - was Andrés Manuel López Obrador who is popularly known as Amlo. He is the populist former mayor of Mexico City who previously stood for the presidency as the candidate of The Party of the Democratic Revolution (PRD). This time he ran for the party he founded in 2014: the Movement for National Regeneration or Morena. He took office on 1 December 2018.

It should be noted that Mexico does not have a vice-president. The constitution provides a process whereby, in the event that the presidency becomes vacant before the scheduled election, the Congress chooses a temporary president and then holds a new election.


The Mexican legislature is the bicameral Congress of the Union, composed of a lower house called the Chamber of Deputies and an upper house called the Senate of the Republic. The Congress makes federal law, declares war, imposes taxes, approves the national budget and international treaties, and ratifies diplomatic appointments.

The Chamber of Deputies

Originally the Chamber of Deputies consisted of 178 congressional districts each filled by plurality or majority vote. However, the semi-authoritarian Institutional Revolutionary Party (PRI) exercised such a tight grip on political expression and organisation that between 1949 and 1961 the PRI lost a mere 33 seats out of a total of 807 district contests.

In the face of increasing criticism of this political model, in 1964 the PRI decided to add additional seats based on the percentage of votes won by the opposition parties. Between 1964 and 1979, these extra seats numbered between 36-41. So the size of the chamber increased from 178 to 219. Most of these extra seats went to the National Action Party (PAN). The PRI introduced this change to create the impression that the electoral system was more democratic and competitive than was actually the case.

Then, in 1977, new legislation increased the number of district seats filled by majority vote from 178 to 300 and allocated 100 more seats to be allocated on the basis of the party's overall share of the vote in the election. So this time the Chamber increased from 219 to 400. Years later, the number of seats awarded through proportional representation went up from 100 to 200, making the total number of Deputies 500.

On the one hand, one could - and many Mexicans have - criticise this expansion in the Chamber of Deputies which represents an increase of 180% on the original size of the Chamber and makes it four times the size of the Senate. On the other hand, one could argue that the sizes of the two chambers are similar to the sizes of the two legislative chambers in the political system of the USA.

So today the Chamber of Deputies has 500 deputies. Of these, 300 are elected by plurality vote in single-member districts (the federal electoral districts) and 200 are elected by proportional representation with closed party lists for which the country is divided into five electoral constituencies.

Elections to the Chamber of Deputies are held every three years, every second election coinciding with elections to the Senate and the Presidency. Nobody can serve more than two consecutive terms - totalling six years - as a Deputy.

The Senate Of The Republic

The Senate is made up of 128 senators. Of these, 64 senators (two for each state) are elected by plurality vote in pairs - 32 senators are the first minority or first-runner up (one for each state) - and 32 are elected by proportional representation from national closed party lists.

Elections to the Senate are held every six years, each such election coinciding the election to the Presidency.


For many decades, there was growing concern that elections in Mexico were not free and fair. The Institutional Revolutionary Party (PRI) was accused of ballot-rigging and media manipulation.

The growing strength of the National Action Party (PAN) and the Party of the Democratic Revolution (PRD) in the congress led in the early 1990s to the creation of the Federal Electoral Institute and the Federal Electoral Court plus public funding for all political parties.

The Federal Electoral Institute, which was created in 1990, has complete control over elections. In 1996, it achieved more independence when it became an agency outside government whose nine members are selected by Congress. The president is selected for a six-year term and may not be reappointed. The regular members are selected for a term of nine years and may not be reappointed.

The Federal Electoral Court, which was cretaed in 1996, hears appeals against the results of elections. Appeals may be lodged by candidates and parties.


There are three major political parties in Mexico.

The Institutional Revolutionary Party (PRI)

This was created in 1929 when it was called the National Revolutionary Party (PNR). It was formed at the initiative of Plutarco Elías Calles who was president from 1924-1928 but was concerned for the political stability of the nation when his elected successor (Álvaro Obregón) was assassinated before taking office. In 1938, the party changed its name to the Party of the Mexican Revolution PRM). Then, in 1946, it adopted its third and current name, the Institutional Revolutionary Party (PRI):

Astonishingly in a so-called democracy, this one party won every state governor race until 1989, most seats in the Chamber of Deputies and the Senate until the 1990s, and all presidential elections until 2000. Although it failed to win the presidency in the elections of 2000 and 2006, it was successful in the presidential election of 2012.

The National Action Party (PAN)

This party was founded in 1939 by dissident politicians from the Mexican government and other leading political activists searching for an ideological alternative to the then PNR (then PRM, now PRI). It grew very slowly under politically adverse circumstances at the state and local levels and did not make significant headway until the electoral reforms of 1964 which assigned a small number of 'party seats' to the opposition parties in the Chamber of Deputies.

Then the PAN managed to win the presidential elections of both 2000 and 2006. More recently, the successful PAN canidate in 2000 Vicente Fox backed the PRI presidential candidate in 2012 and was expelled from the party.

The Party of the Democratic Revolution (PRD)

This party was only founded in 1988 in the longer-term aftermath of the PRI government responding with violence to students protests in 1968. The party was an amalgam of Left-of-Centre parties and numerous defectors from the PRI who favoured fair elections and more state support for social programmes of expenditure. In the 2006 presidential election, the PRD candidate almost won.

The party has recently been seriously weakened by the withdrawal of several constituent parties, most notably the party led by the controversial populist politician López Obrador who ran unsuccessfully as the PRD candidate for the presidency in both 2006 and 2012 and is in a strong position to win in 2018.

Pact for Mexico

The Pact for Mexico is a national political agreement signed on 2 December 2012 by the political parties PRI, PAN and PRD (the PRD left the Pact in November 2013). The Pact and a subsequent addendum contain a total of 106 public policy commitments. Supporters of the Pact assert that it has broken parliamentary gridlock and enabled the enactment of important pieces of legislation. Critics of the Pact claim that it has made political negotiations more opaque and weakened the legislature in relation to the executive.


The key organisations outside government that influence public policy in Mexico are as follows


The head of the Mexican judicial system is the Supreme Court of Justice. The court has 11 members who are nominated by the President and must be approved by two-thirds of the Senate.

Each member of the court serves for a limit of 15 years or less if he or she reaches mandatory retirement age. An appointee is not allowed to have held a public office one year prior to his or her appointment.

Since the mid 1990s, the court has been able to rule on the constitutionality of laws.


The Constitution of the United Mexican States provides that there will be three levels of government: federal, state and municipal. Below the federal level, there are 32 states (one of which is the capital Mexico City).

According to the constitution, all constituent states of the federation must have a government composed of three branches: the executive, represented by a governor and an appointed cabinet, the legislative branch constituted by a unicameral congress, and the judiciary.

Like the federal Congress, the state legislatures, are elected by a system of parallel voting that includes plurality and proportional representation.

Each municipality elects a mayor and this is the one exception in the Mexican political world where an office holder can run for a second term. Each term lasts three years so one person can serve two consecutive terms.

Each state has a local version of the Federal Electoral Institute that is responsible for all state and local elections.

In state elections held in June 2016, the Institutional Revolutionary Party (PRI) came into the elections holding nine of the 12 governor seats that were being contested, but it held only five of those seats. Its chief rival, the conservative National Action Party (PAN) won the governor's offices in the other seven states, including three in a strategic alliance with the left-leaning Democratic Revolution Party (PRD).


At one level, Mexico's political experience has been exceptional compared to the rest of Latin America (excluding Costa Rica) in that, since the 1950s, most other nations in the region have suffered military dictatorships or military control over civilian governments, but Mexico has managed to keep the military out of politics since the 1930s.

On the other hand, except for a very brief period in 1911, Mexico had no experience of competitive electoral politics for most of the 20th century even while most other Latin American countries achieved electoral democracies by the 1980s.

In the last decade and a half, Mexico has shown itself capable of changing the political composition of its presidency through genuinely competitive elections, but the country is still in a process of democratic consolidation with much work still needing to be done to eliminate bribery and corruption and achieve full accountability and transparency.

Meanwhile Mexican politics is a turbulent and personal affair and the political establishment does not easily respond to grass roots demands. As one Mexican put it to me: "You need to be noisy to be heard".


Last modified on 6 December 2018

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