MEXICO CITY — Mexico's Supreme Court on Thursday rejected a bid to hold a national referendum on a major energy overhaul that opened the sector to widespread private investment for the first time in 76 years.
In identical 9-1 rulings, the court found that referendum petitions filed by two leftist parties were unconstitutional because matters involving state revenue cannot be subjected to popular vote.
Energy reform's passage in August has been President Enrique Pena Nieto's biggest political victory since taking office in 2012.
It allows national and foreign private companies to invest in petroleum and electricity projects, something that was long considered taboo after oil was nationalized in 1938 by then-President Lazaro Cardenas.
Mexico's political left strenuously opposed the overhaul and had sought a referendum asking citizens if they approve of the constitutional changes it entailed. By law, the Supreme Court must determine whether such a vote would be constitutional.
Sen. Dolores Padierna of the opposition Democratic Revolution Party criticized the ruling, saying the issue at stake is not government income but rather "our natural resources ... (and) their use for the nation's benefit."
Proponents of the changes say private investment and expertise is needed to reverse a steady decline in oil and gas production by state petroleum monopoly Pemex in recent years.
Analysts say energy investment has the potential to reach $15 billion a year under the new rules.