MEXICO CITY (AP) — Mexico’s Supreme Court ruled Thursday the president can go ahead with a proposed referendum on prosecuting ex-presidents.

Opponents had claimed it violated the precept that the decision to prosecute should be made by prosecutors, not voters or politicians.

The court ruled in a 6-5 vote that the measure was constitutional, but said the wording of the question to appear on ballots might be modified.

As submitted by President Andrés Manuel López Obrador, the referendum question states: “Do you agree or not that the relevant authorities should, in accordance with the applicable laws and procedures, investigate and if appropriate punish, the presumed crimes committed by former presidents” and then goes on to name five of Mexico’s six living ex-presidents.

The sixth, Luís Echeverria, served from 1970 to 1976 and is 98 years old. A specialized prosecutor’s office filed charges against Echeverria for a 1968 student massacre, but a tribunal exonerated him in 2007.

López Obrador proposed the referendum for June 6, 2021, the date of midterm congressional elections that are key for holding on to López Obrador’s bare majority in Congress.

The referendum could be a way of drawing voters to the polls, because midterm votes in Mexico often have low turnout, and it could deflect attention from the current administration’s problems with the economy and coronavirus pandemic, by focusing attention on past abuses.

López Obrador views the referendum as an indictment of corruption, conservative economic programs and privatizations, not just what he claimed was “systematic corruption” since 1988.

“The social and humanitarian disasters we have suffered in this country over the last 30 years were the result of a series of conscious acts by those who governed during this period,” López Obrador said. “The evils I have enumerated did not occur by chance, but rather were the result of the application of a model over five presidential terms … this tragic stage in the life of the country is called the neoliberal era.”

Acts of corruption can be punished under current law, but it is unclear whether López Obrador can investigate former leaders for policy decisions he disagrees with, like the widespread privatizations of government companies carried out by Carlos Salinas de Gortari, who governed Mexico from 1988 to 1994.

The president appeared to equate those policies with corruption; insiders were often given sweetheart deals on government contracts or privatizations.

“In the neoliberal period, corruption became the main function of political power,” he said. In the past, López Obrador had shied away from delving into past presidents’ misdeeds, saying “revenge is not my strong point” and “forgive and forget.”