Haiti's Supreme Court has overturned the convictions of dozens of military leaders found guilty in 2000 of murder and torture.
Louis-Jodel Chamblain could now be released from prison
They were convicted of mass killings during an attack on supporters of former President Jean-Bertrand Aristide in the shanty town of Raboteau in 1994.
The government of Prime Minister Gerard Latortue says it did not influence the judges' decision.
But Aristide supporters were outraged, calling it a "partisan" decision.
It says that the original court which tried the men had lacked the authority to hear the case.
"The court... overturns the judgment without referring to another court and orders that all those accused be released if there are no further charges against them," the Supreme Court said in a 3 May ruling released on Tuesday.
The trial was carried out in 2000 in the absence of most of the accused, many of whom were in exile. Some have since been jailed, but it is not clear exactly how many.
Following Tuesday's announcement, AFP news agency reported that the court has set free 14 of the officials.
The report did not name them, but Louis-Jodel Chamblain, one of the leaders of last year's uprising against Mr Aristide, could be among them.
At least 15 people died in the raid on Raboteau, a seaside shanty town in north-west Gonaives.
It targeted supporters of Mr Aristide, who was democratically elected president in 1991 but ousted the same year.
He was returned to power in 1994, with US support. Last year he was overturned for a second time.
Before reports on the court's decision were confirmed, Interim Prime Minister Gerard Latortue said Haitian judges reached their conclusions freely.
"All our lives we have fought against the interference of the executive in judicial affairs," he told the Associated Press news agency.
Later one of Mr Latortue's aides told Reuters news agency: "The government had nothing to do with the decision of the Supreme Court, which is part of an independent power."
But Gerard Gilles, a former senator in Mr Aristide's Lavalas Party, said the ruling proved the opposite.
"This shows the current government is partisan, revengeful, hateful and not serious about justice," he said.
The US lawyer who had helped to prepare the case against the convicted men, Brian Concannon, called the decision a complete reversal of the long effort to establish justice in Haiti.
"The trial... stood for the possibility of justice in Haiti. It was praised as a landmark in the fight against impunity," he said.