The Desafuero of Andrés Manuel López Obrador was the removal of López Obrador's (then Mayor of Mexico City) state immunity from prosecution. It took place during 2004 and 2005. This process was originated by a land owner who sued the Federal District's government on the grounds of improper expropriation of a patch of land called El Encino. This case detonated in López Obrador's (AMLO) hands in 2005, when a vote by the Chamber of Deputies lifted his constitutional immunity against criminal charges. If officially charged, he would have lost all his civil rights, including the right to run for the presidency in 2006, unless he was either quickly acquitted of all charges or managed to serve his sentence before the electoral registration deadline.
The desafuero was supported by the then-ruling PAN, the federal government headed by then-President Vicente Fox, and the PRI; it was opposed by the PRD (the party in which López Obrador was afilliated) and left-wing politicians. The process lasted for more than a year and resulted in a polarization among Mexican society between those who supported the desafuero and those who opposed it.
After a massive rally in support of López Obrador took place in Mexico City on April 24, 2005, with an attendance exceeding one million people (at the time, the biggest political manifestation in recent Mexican history), and near unanimous condemn from the foreign media towards the process, president Vicente Fox decided to stop the judicial process against López Obrador.
On April 27, 2005, President Vicente Fox announced changes in his cabinet, a re-evaluation of the legal case against AMLO and legal changes so civil rights are only suspended once a citizen is found guilty. Fox and López Obrador met in the first week of May 2005, as part of the efforts to calm the political climate. The new Attorney General found a way to avoid prosecuting López Obrador, but it depended on the approval of the private company that first sued him.
The 111th article of the Mexican Constitution states that most high-level elected officials cannot be prosecuted for criminal offenses while in office without a simple majority vote of the Chamber of Deputies stating there are grounds for prosecution. This privilege is usually confused with the freedom of speech protection granted to members of congress by the 61st article, known as fuero (from Latinforum), the process to strip it is known as desafuero. Since immunity from criminal prosecution is almost universally confused with the fuero, both terms will be used interchangeably.
If the Chamber of Deputies votes in the negative, the prosecution can still take place when the official leaves his post, as deputies don't vote on the accusation itself but only on whether there is a reasonable belief that a crime was committed. If it votes in favor, the official can be prosecuted. A secondary law states in this case the official loses his office immediately.
The constitution mandates that state governors are subject to their state congresses; it should be noted the Federal District is not a state.
An individual facing criminal prosecution has his political rights suspended (38th article) so he cannot run for office or hold one, at least temporarily. All candidates for the presidential election in July 2006 were required to register no later than January 15, 2006, although the law does allow a change of candidate until May of the same year.
The legal system is mostly untested in cases like this, and the special status of the Federal District (it is not a state; until recently it was governed by a departmental head appointed by the president; it has a legislative assembly that is not a state congress) will lead to appeals and legal controversies before the Supreme Court.