Northern Ireland's Public Prosecution Service has said it regrets an administrative error that meant charges against three men accused of assaulting police at a republican parade were dismissed.
A PPS lawyer failed to turn up at Enniskillen magistrates court to argue the case two weeks ago.
The service said that it had put additional measures in place.
Alex Elliott of the TUV said the error should never have happened.
"I served as a police officer for 31 years and if I had failed to turn up for court, on my arrival, I would have had to apologise, I would have been investigated by the police authorities and disciplined," he said.
"There needs to be an investigation into what went wrong and it must never happen again."