Increasingly competitive elections were the backbone of the transition to democracy in Mexico, prompting some scholars to call it a "voted transition." Successive electoral negotiations, particularly between 1989 and 1996, increased opposition parties' victories at the local, state, and federal levels, and eroded PRI hegemony.[6] The role of the Federal Electoral Institute (IFE), established in 1990 to manage and oversee elections, was particularly important. Although it was initially controlled by the federal government, it gained full independence in 1996, becoming an organization that was staffed by professionals and led by consejeros ciudadanos (citizen counselors) rather than politicians. However, given that the lower chamber of Congress is in charge of appointing the counselors, the composition of the IFE's nine-member General Council has tended to reflect the balance of power in that chamber. The judicial branch was brought into the electoral arena with the creation of the Electoral Tribunal of the Federal Judiciary (TEPJF) in 1996. Seven magistrates preside over the tribunal, and their impartiality has generally been praised by leaders across the political spectrum, with some complaints regarding the adjudication of fines for violations of campaign finance norms.

The federal government provides all parties with generous public financing. In 2008, for example, the IFE provided a total of US$250 million, 30 percent of which was distributed equally among the eight parties represented in the bicameral Congress, regardless of the size of their delegations. In the Congress of 2006–09, the PAN held 207 Chamber of Deputies seats and 52 Senate seats, the PRD held 127 and 26, and the PRI held 106 and 33. Smaller parties and independents accounted for the remainder. While the even distribution of this 30 percent enhanced the equality of campaigning opportunities, the rest of the financing was allocated according to each party's representation in the 300 directly elected Chamber of Deputies seats (the other 200 seats in the 500-seat lower house are filled through proportional representation). This part of the formula naturally benefited the largest parties.[7]

The opportunity for regular rotation of power among different parties is well established at the federal level, but the left denounced foul play in the 1988 and 2006 presidential elections. The blatant nature of 1988's fraud eventually served to strengthen Mexico's democratic movement. Conversely, the refusal in 2006 of PRD candidate Andrés Manuel López Obrador and his allies to recognize Calderón's victory, and the months of protest that followed, weakened the left, while also deepening its suspicions that, absent a landslide victory, powerful business and political forces would act aggressively to prevent a transfer of power.

At the subnational level, there are a handful of states, such as Chihuahua and Nuevo León, where power has shifted over time from the PRI to the PAN and then back to the PRI, suggesting that such alternation has become increasingly part of the routine of democratic politics. On the other hand, in at least 13 of the 31 states, the PRI remains undefeated in gubernatorial elections. In some of these cases the traditional image of powerful caciques (local political bosses) remains an everyday reality. The same applies at the municipal level, where the three main parties have developed political machines with solid voting clienteles. More often than not, the PAN and the PRD, which had long criticized the PRI's patronage and clientelism while they were in opposition, have replicated this style of politics once in power.

Regulations to prevent the undue influence of economically privileged interests became one of the main points of contention after the July 2006 presidential election, which was decided by less than 0.5 percent of some 42 million ballots.[8] Legal uncertainty over campaign finance rules allowed dominant economic groups to provide a last-minute wave of financial support to PAN candidate Calderón, which fueled a media offensive against the fiery populist López Obrador in the run-up to election day. The media onslaught allowed Calderón to close a gap in voter support that stood at about 10 percentage points 90 days before the vote.

Once in office, President Calderón accommodated PRD and PRI calls for electoral reform legislation, which was enacted in November 2007. In an effort to create a more level playing field, the reform "cut the length of presidential campaigns almost by half [to just three months prior to election day], gave the IFE power to regulate party primaries, cut public funding to political parties, and banned all political advertising outside of officially arranged time slots."[9] It did not lift the ban on independent candidates for federal races, a change some have called for in order to shake up what is viewed as Mexico's partidocracia (rule by the leaders of political parties).

The new regulations faced their first test with the midterm elections of July 2009 and appear to have functioned largely as intended, despite some grumbling and complaints of cheating. In the balloting, the ruling PAN and the PRD suffered crushing defeats (the PAN won 147 seats, losing 59; the PRD won 72 seats, losing 51; and four smaller parties—the Green Party, Labor Party, New Alliance Party, and Convergence—won 40 seats). The PRI, in a spectacular comeback in Congress, will have 241 seats in the lower chamber, a net gain of 135 seats. The PRI also won five of six governorships in dispute, making it the early favorite to win the 2012 presidential elections. A movement arose during the campaign urging voters to show their displeasure with the political class by casting a null vote, but less than 6 percent of voters did so.

The three branches of government counterbalance one another significantly, increasing effectiveness and accountability. The most important change since the mid-1990s has been the weakening of the previously "imperial" presidency and the associated rise of the legislative and judicial branches. The Mexican presidency lacks the decree powers, "fast-track" authority, and other legislative prerogatives found in many other Latin American presidential systems.[10] The rival parties have been at loggerheads over highly politicized issues such as pensions, fiscal policy, energy, and labor law, but even in these areas mild reforms—which do not address Mexico's underlying economic problems—have been successfully implemented under President Calderón. The chances of further structural reforms decreased significantly given the PAN's defeat in the 2009 midterm elections.

Freedom of political choice varies according to locality. Whereas in the aggregate Mexico comes across as a proper electoral democracy with free and fair elections, growing concern surrounds the political influence of criminal groups. Estimates in September 2008 suggested that 8 percent of Mexico's roughly 2,500 municipalities were under the "total" control of drug traffickers, while they exercised "some" control in close to 60 percent of all local governments.[11] The current fear is that organized criminals' financial clout and capacity to carry out threats could have provided them with the means to clandestinely impose candidates for the 2009 elections.

The Professional Civil Service Law creates a framework that encourages employment and promotion based on open competition and merit. However, it applies only to the federal government, and even there, it focuses on senior and mid-level officials.[12] Most positions in the federal, state, and local bureaucracies are up for grabs whenever there is a change in government.

Civic engagement and monitoring have grown gradually in Mexico since the late 1980s. As political power has shifted from the presidency toward Congress, advocacy and lobbying have become lucrative, full-time, professional occupations. Such activities have a substantial influence on government policy and pending legislation. While legal impediments to registration are minimal, the absence of laws and regulations on lobbying tends to favor the efforts of big firms with abundant financial and technical resources, as opposed to nonprofit advocacy organizations, and the establishment of normative lobbying practices is undermined by the ban on reelection in Congress. Deputies serve three years and senators six, after which they have to step down, and their accumulated experience in dealing with pressure groups goes with them.[13] Meanwhile, because state and local governments are more driven by patronage and clientelistic practices than officials at the federal level, they are less inclined to foster the transparency that civic organizations need to engage in effective oversight. Most nongovernmental organizations (NGOs) are able to carry out their work vigorously, but NGO workers in some regions, particularly in southern rural zones, are at times subject to threats and intimidation (see Civil Liberties).

Full legal protections for freedom of expression have existed on paper since the years of PRI rule, but in practice the proper exercise of this right developed very gradually. In its hegemonic heyday the PRI exerted its influence by withholding state advertising from publications and broadcasters that engaged in political dissent. In some cases the authorities would resort to intimidation or coercion. The decline of PRI hegemony, particularly during the 1990s, allowed the emergence of an environment that was more conducive to media freedom. This process has been bolstered by the growing role of the internet, which is not hindered by the state. In April 2008, President Calderón signed a law that decriminalized defamation and "insults" and obliged state governments to follow suit. However, as of July 2009 defamation was still criminalized in 21 of 32 states.[14]

Although the media is often vibrant, the expansion of media freedom remains territorially uneven. Some state and municipal governments burden critical media outlets with frequent audits, threats to revoke licenses, or direct intimidation. However, the single greatest threat to media independence and freedom of expression in Mexico is organized crime's growing capacity to menace the owners of print and broadcast media, and to kill—in some cases after sadistic torture—journalists who cover organized crime and law enforcement. At the end of 2008, the World Association of Newspapers (WAN) reported that 23 journalists had been killed since 2000, and seven others had disappeared since 2005. The organization said that made Mexico more dangerous for the media than any country in the Americas. WAN noted that none of the perpetrators of journalists' murders since the start of the war against organized crime have been brought to justice.[15] This impunity has encouraged self-censorship in violent regions, and many newspapers in these areas no longer publish bylines on stories about organized crime. In an emblematic case, TV Azteca reporter Gamaliel López and cameraman Gerardo Paredes vanished in May 2007 in the northeastern state of Nuevo León. López had reported for six months on the local presence of the army and had exposed corruption. A different but also troubling dynamic applies in the southern state of Oaxaca, where Indymedia cameraman Brad Will, a U.S. citizen, was killed during unrest in late 2006. El Tiempo reporter Misael Sánchez Sarmiento, who investigated Will's death, was shot and wounded by a gunman in June 2007. Preliminary investigations as well as recommendations by the Mexican National Commission for Human Rights (CNDH) indicate that fundamental principles of legality and judicial security have been severely violated in the processing of Will's case.  In 2009, those responsible for Will's death remained at large.[16]  

Given the centrality of elections in Mexico's young democracy, control over media content during campaigns has been the focus of acute conflict. As noted, the uneven use of the media in the run-up to the 2006 presidential election was so obvious that Calderón, after taking office, quickly supported opposition demands for a new electoral reform. Media conglomerates considered the 2007 reform draconian because it banned political advertising outside of officially arranged time slots, but public opinion strongly favored such limits. Estimates suggest that 80 percent of the US$324 million that parties spent in the 2006 federal elections went to the private media. This use of public money was especially egregious given that the television market is essentially a duopoly dominated by Televisa (7 in 10 Mexicans get their news from its outlets) and TV Azteca (which accounts for 2 of the remaining 3). Radio broadcasting is also concentrated, although 13 different private groups participate nationally.[17] Televisa, which wields great financial and political clout and maintains a dominant position as shaper of Mexican public opinion, is one of Mexico's most powerful actors and is the subject of intense political debate and controversy. One illustrative incident pitted the media conglomerate against well-known journalist Carmen Aristégui, who argued that her December 2007 exit from a popular radio show she conducted on W Radio (a station part-owned by Televisa), was politically motivated. She also alleged that Televisa under-reports stories adverse to State of Mexico governor Enrique Peña Nieto, the early PRI front-runner for the 2012 presidential race, a charge strongly denied by Televisa.