The recent court case following the murder of Temixco mayor Gisela Mota highlighted the growing pains of the new system.
It was once unthinkable in Mexico: A courtroom open to the public, with a prosecutor presenting evidence against murder suspects in a deadpan tone while a lawyer argues against it.
Mexico is embracing US-style open courts and ditching an opaque system more than a century old in which prosecutors and defense lawyers make their cases through mountains of paperwork and judges mete out sentences without seeing the suspect's face.
Authorities are racing against the clock to meet a June 18 deadline to install the accusatory system in all 32 federal entities as part of judicial reform passed in 2008.
Seven states are ready while the remaining 25 have been dragging their feet, only partially implementing the new system.
"Mexico has made a titanic effort," said Maria de los Angeles Fromow, a federal official coordinating the implementation.
"We are transforming and strengthening the rule of law by making it efficient and transparent," Fromow said.
- Anonymous envelope -
A recent court case in the central state of Morelos highlighted the growing pains for prosecutors and lawyers unaccustomed to using the spoken word, rather than paper, to make their cases.
A month after the mayor of Temixco was murdered, two new suspects were brought to a modern court in February to face charges over the killing.
The accused were in street clothes and without handcuffs, a big change from the old system, where they would have worn prison uniforms.
But in a key moment, their lawyer barely questioned the main piece of evidence presented by the prosecutor.
It was a yellow envelope left anonymously at the door of the mayor's house a few days after gunmen forced her from her room and shot her dead in front of her parents.
Written on the envelope, addressed to her mother: "If you want to know who killed your daughter, open it." Inside were pictures of three people, including the two men in court.
The judge ruled that the evidence was sufficient to send the case to trial on murder charges.
While the new system may not be perfect, "nothing is worse than what we have now," an instructor recently told a group of journalists during a course on how to cover oral arguments.
The old system has been mired in flaws that were exposed in the 2011 documentary "Presumed Guilty," about a man who was sentenced to 20 years in prison, based on false testimony, for a murder that he did not commit. He was acquitted thanks to appeals from the documentary makers.
The US government has trained 30,000 Mexican judges, prosecutors and lawyers and spent $250 million to help its southern neighbor transition to the new system as part of a crime-fighting aid program.
The European Union, Chile and Colombia have also provided assistance to Mexico, which has come late to the game, with Costa Rica switching to the accusatory system in 1975 and other Latin American countries following suit.
But the country's federal regions have been slow to change their ways, with 23 of 32 states waiting until 2014 and 2015 to set up courts and train judges and other staff.
"No delays will be allowed to implement the system," President Enrique Pena Nieto said recently.
While there is no threat of losing federal funds for states that fail to comply, Fromow said the penalty would be that authorities would see their cases challenged by lawyers.
- A woman's death -
The new system seeks to end widespread impunity and reduce the prison population, where many inmates include suspects who have yet to be put on trial.
A study in states that are using the accusatory system shows cases are being processed much faster, with resolutions or sentences within 150-180 days compared to more than 500 days under the old system.
But one high-profile case exposed problems in the system.
In 2010, a woman was gunned down in front of the Chihuahua state government building after she publicly decried the acquittal of a man accused of murdering her 16-year-old daughter, even though the suspect had confessed to the crime.
"It created a very negative perception of the system nationally," said Raul Carrillo del Muro, head of a law school in the state of Zacatecas, adding that people thought such trials were overly protective of the rights of suspects.
