Demonstrators hold images of some of the 43 missing students from a teachers’ college during a protest to mark the six-month anniversary of their disappearance in Mexico City in March. (Marco Ugarte/AP)

One day, it’s police and soldiers killing civilians. The next, top government officials lapping up perks of wealth and power.

After months of scandals and public outcry, the administration of President Enrique Peña Nieto has endorsed new anti-corruption measures that many hope will begin to rebuild Mexicans’ lack of trust in their government.

Peña Nieto’s popularity has fallen over the past year as public crises have rocked his government and contributed to an impression that Mexico is becoming an increasingly consequence-free zone for political corruption.

The new anti-corruption system passed this week by Mexico’s Congress, which must be approved by the majority of the states, is designed to give more authority and independence to investigative bodies. Audits of government spending will be able to occur more frequently and at the state level. The appointment of the head of the Public Administration Ministry will have to be approved by Congress.

“Unfortunately, the economy in our country is built on links and relations between men of power,” Graco Ramirez, the governor of Morelos, said in an interview. “And this relationship has to be revised so we have real rules of the market and so regulators can function.”

Supporters of the program consider it significant because it puts more emphasis on state spending, which has been less scrutinized than the federal government. There’s still plenty of skepticism about whether the changes on paper will translate into actual investigations and prosecutions of top officials.

“This is not a panacea to change corruption. But it touches on something that is very important,” said Viridiana Rios, the founder of Mexico Como Vamos, a think tank. “It’s a beginning of a change of the discourse in this country.”

Her organization’s Web site now has a ticking clock counting the time it takes each governor to approve the new anti-corruption rules. It is this type of citizen pressure, she said, that has helped put the issue on the political agenda.

“This is the reform of civil society,” Rios said. “It is our job to push them to do what they need to do.”

After more than a year of productive constitutional restructuring driven by Peña Nieto that shook up monopolies, revised the tax and educational systems, and opened up the oil industry to foreign investment for the first time in decades, a series of scandals have rocked his presidency.

The gravest was the disappearance and likely deaths of 43 students at a teachers’ college in the state of Guerrero in the fall. Authorities have blamed local police and politicians for colluding with drug cartel henchmen to carry out the massacre. Street protests roiled the country for months.

This was followed by revelations that Peña Nieto’s wife and his finance minister made deals to buy houses from a favored government contractor. A $3.7 billion contract awarded to Chinese and Mexican companies to build a high-speed train out of Mexico City was canceled amid suspicions about its fairness. Earlier this month, the head of the national water commission resigned after using a government helicopter for a family outing.

“[Peña Nieto] wasn’t aware that you also have to change the practices of power,” said the Morelos governor, Ramirez, a member of the opposition Democratic Revolutionary Party. “It’s unfortunate because he had the bravery to do reforms that many didn’t want to because of the political cost. But it’s also unfortunate that he hasn’t corrected how politics is practiced.”

The new anti-corruption program comes at a time when the fairness of public spending will face one of its biggest tests. With the opening of the oil industry to foreign investment, there will be billions of dollars of contracts with international companies. For those investing in this environment, the new rules could mean less risk, said Matteson Ellis, an international anti-corruption lawyer who specializes in Latin America.

“This will be a highly significant development for the international business community,” he said. “It gets directly at the issue of impunity. No longer is a U.S. company forced to tell its Mexican business partner, you’ve got to comply with this law in the U.S. Now they can say, you need to comply with your own laws.”

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Today’s coverage from Post correspondents around the world