MANILA (Reuters) - The head of a southern Philippine political clan sparked courtroom gasps on Wednesday when he denied 57 charges of murder in a November 2009 massacre that shocked a nation accustomed to political violence.
The case has been cast as a test of a much-criticized justice system and the resolve of President Benigno Aquino to deliver on promises to implement the rule of law by ending a culture of impunity for the politically well-connected.
Andal Ampatuan Sr's plea and arraignment came 18 months after the killings and four months after his petition to have the charges thrown out was dismissed, underscoring the slow progress of a case expected to last longer than Aquino's six-year term.
The victims, including more than 30 journalists, were traveling to witness the filing of papers for a candidate to stand against Ampatuan Jr in the May 2010 elections when they were stopped by armed men on a mountain road in Maguindanao.
They were taken down a dirt road and shot and buried in mass graves. Some victims were buried in their vehicles.
"The government's case against dozens of defendants in the 2009 massacre in Maguindanao province... reflects an overall pattern in which Philippine authorities often identify suspects but rarely win convictions," the Committee to Protect Journalists (CPJ) said in its 2011 Impunity Index report.
After the 57 charges of murder were read out in a local dialect by an interpreter, with each victim named, Ampatuan Sr pleaded not guilty.
His plea sparked gasps and shouts from families of the victims in the court, specially set up inside a Manila prison, prompting a rebuke from the judge.
Ampatuan Sr's trial is set to begin on June 15. He will be tried with his son, Andal Ampatuan Jr, who is accused of masterminding the killings.
"We're happy because he is really here. He's faced the victims' relatives, and the arraignment has taken place," said Juliet Evardo, mother of one of the victims.
"We've been clamoring for this for a long time."
Ampatuan's plea came on the same day the CPJ said the Philippines ranked third, behind Iraq and Somalia, in its Impunity Index for 2011, which calculates unsolved journalist murders as a percentage of a country's population.
The CPJ says there are 56 unsolved murders of journalists in the Philippines.
"Initial trial proceedings in the Maguindanao killings have been plagued by threats and bribes targeting witnesses, and incompetence and corruption among local investigators," it said, noting there had been no convictions in the case.
Prosecutors have charged nearly 200 people, including three of Ampatuan Jr's brothers and an uncle, over the massacre, the worst single incident of political violence in the Philippines. Most of the accused remain at large, and 57 have been arraigned.
The Ampatuans ruled Maguindanao for nearly a decade and were strong supporters of former President Gloria Macapagal Arroyo.
(Reporting by Michaela Cabrera; Writing by John Mair; Editing by Nick Macfie)