Mexico's new Supreme Court will likely heavily favor Sheinbaum's ruling party

Judges aligned with Mexican President Claudia Sheinbaum's ruling Morena political party are expected to dominate the country's Supreme Court after a vote that critics feared would weaken checks and balances on the executive branch's power.

Sunday's unprecedented election will usher in nine Supreme Court justices, reduced from 11 previously appointed by various presidents. Most of those resigned over the judicial reform that spawned the vote and declined to participate in the elections.

The voters who turned out - just 13 per cent of the electorate - also chose more than 840 federal judges and magistrates positions, and thousands more at the local and state level.

With nearly all votes counted by the end of Tuesday, the reconfigured Supreme Court looked to be dominated by justices affiliated with Morena through political posts. Several were previously endorsed by former President Andres Manuel Lopez Obrador, who pushed through the reform in his final months in office.

Lopez Obrador and Sheinbaum - his protégé - argued the reform was necessary to root out corruption in Mexico's flawed judicial system and make it more accessible to citizens.

Critics of the reform, one of the most broad-ranging to be attempted in recent years by any country in the Western hemisphere, warned it would remove checks and balances on Morena, undermine democracy and boost powerful drug cartels' ability to influence the judicial system.

The elections appear to put Morena, which already holds a majority in both houses of Congress, on the verge of controlling all three branches of Mexico's government.

"It seems like the court that is going to form is one that Lopez Obrador always dreamed of having when he was president," said Laurence Pantin, co-coordinator of the Justice Observatory at Tec de Monterrey and director of the civil organization Fair Trial.

"The objective, to be clear, was to have a judicial branch submissive to the executive branch," Pantin said.

Some experts attribute Lopez Obrador's zeal to overhaul the judiciary to his tense relationship with the Supreme Court during his presidency from 2018 to 2024. The high court was often a roadblock to his policies, including curtailing the power of election authority INE and bringing the National Guard under control of the military.

While Lopez Obrador ultimately found ways to accomplish most of his agenda, the Supreme Court served as an important check on his powers, said Gustavo Flores-Macias, a public policy professor at Cornell University.

As Sheinbaum seeks to build on his legacy, she is likely to see much weaker resistance from the courts. That could help grease the wheels for her to further empower the armed forces to participate in civilian affairs or brush off procedural constraints on infrastructure projects.

Lopez Obrador faced pushback from the court within the energy sector, too. A single-partisan judiciary could make it much easier for the government to circumvent environmental obligations or investor protections under the US-Mexico-Canada trade agreement.

"The optics are not great," Flores-Macias said. "It's very difficult to envision the Supreme Court serving as any counterbalance on these policies that the president will look to advance, especially with a majority in Congress," he added.

While giving Morena a free hand to implement its agenda in the coming months and years, the stacking of the court with allies could also rob Sheinbaum and her party of one of Lopez Obrador's favorite scapegoats for his setbacks, Flores-Macias said.

Sheinbaum heavily promoted the elections leading up to the vote, calling them an example of a strong democracy, in which judges and magistrates could answer to the people.

But the low turnout has already prompted threats of legal challenges by the opposition.

Alejandro Moreno, leader of the opposition Institutional Revolutionary Party, called for the election results to be annulled, blasting the vote as a "farce" that had "nothing to do with democracy."

"We will be heading towards an authoritarian government, a dictatorship, and these people from Morena don't care," Moreno said in a press conference on Monday.

While justices on the prior high court who were appointed by other presidents resigned over the reform, Lopez Obrador appointees like Yasmin Esquivel Mossa and Loretta Ortiz Ahlf were on the ballot and appear to have secured posts in the elections.

Despite the dangers of single-party domination, the new court's diversity could have some positive effects.

Another Morena-backed candidate, indigenous rights defender Hugo Aguilar, is leading in the race to head the reconfigured court, a choice which could benefit Mexico's underserved indigenous populations, Pantin said.

"It could have a positive aspect because there wasn't much diversity within the court and there hadn't been anyone of indigenous origin on it in recent years," Pantin said.