Cairo: Egypt's court of cassation has refused an appeal by prosecutors over the "Camel Battle" trial.
In October, a court acquitted 24 loyalists of deposed president Hosni Mubarak who had been accused of organising an attack in which assailants on horses and camels charged into crowds of anti-regime protesters on February 1 and 2, 2011.
The 24 were found innocent on charges of manslaughter and attempted murder.
The mounted attack, which included whip-wielding riders, became a symbol of the revolution and led to street clashes.
"The court has made this final decision on the fate of the 24 defendants who were accused of conspiring to kill protesters in that infamous incident," said Al Jazeera's Rawyeh Rageh, reporting from Cairo.
The scenes were televised around the world at the height of the uprising.
"These defendants were acquitted last year, sending shockwaves into the Egyptian community," our correspondent said.
"That has been confirmed today, with the court initially saying that there was not any 'sufficient evidence' to incriminate these men. Surely, a lot of people will be disappointed because Egyptians have been waiting for a long time for anyone to be held accountable in this attack, one of the worst against protesters during the uprising."