In a decision hailed by human rights advocates, the Mexican Supreme Court on Tuesday ordered that military officers and personnel be tried in civilian courts, not military tribunals, when accused of torture, extrajudicial killing and other abuses.

The court's unanimous ruling marks a radical change in the way human rights cases involving the military should be prosecuted. As the number of alleged violations has soared in recent years amid the Mexican drug war, advocates have increasingly and vociferously demanded that the cases be heard by civilian courts.

"This is a very significant advance," said Andres Diaz, an attorney for the Miguel Agustin Pro Juarez Human Rights Center in Mexico City. "It creates very clear principles for Mexican judges."

Human rights groups have long argued that the military could not be trusted to judge its own. There were few prosecutions and even fewer convictions, with most of the proceedings of military tribunals cloaked in secrecy.

The issue became urgent after President Felipe Calderon in December 2006 deployed more than 40,000 troops across the country to fight drug traffickers. Since then, the number of allegations of serious abuse by troops, including forced disappearances, torture and murder, has increased exponentially. The National Human Rights Commission said it had received 4,772 complaints as of July 2.

The Supreme Court's ruling Tuesday was quickly applauded by human rights groups. It remained unclear, however, how quickly cases would be heard by civilian courts, which are notoriously slow and sclerotic. And it was unclear whether the military would comply in all cases.

Last week, the Supreme Court had signaled how it was leaning when it voted to support a 2009 decision by the Inter-American Court of Human Rights that, among other things, found Mexico had failed to investigate the 1974 case of a man allegedly "disappeared" by the military. The international court ordered Mexico to reform its military code of justice, which sends military personnel to military tribunals for trial even when the alleged victims are civilians.

Tuesday's ruling took the next step by ordering all civilian judges to comply with the international court and assume responsibility for cases involving human rights violations by the military.

"Under no circumstances should the military tribunal operate in cases of human rights violations involving civilians," said court Chief Justice Juan Silva Meza.

Nik Steinberg, who covers Mexico for New York-based Human Rights Watch, said the ruling "cuts against" long-standing court practices in Mexico.

"It is a huge, huge step forward and really represents a change in the jurisprudence of the court," Steinberg said. It will also put pressure on Calderon and the Mexican legislature to reform the military code of justice, he added.

In October, Calderon proposed a reform that numerous human rights activists said fell short of what was needed. It would transfer to civilian courts only certain abuse cases involving troops, leaving other serious crimes, including extrajudicial killings, out of the mix. The measure has not passed Congress.

Alberto Herrera, who heads the Mexican chapter of Amnesty International, praised Tuesday's ruling as "historic," noting that it will also force Mexican authorities to comply with other decisions of the international court that require compensation to victims and public apologies.

Herrera also cautioned that civilian justice will not necessarily satisfy victims' demands. He said the "scandalous impunity" that reigns in Mexico is not exclusive to the military but also a product of an ineffective civilian judiciary.

"We can transfer all the cases we want," he told Mexican television, "but if civilian justice doesn't function, none of this will amount to much."