Sex offence convictions against 15 people are to be set aside because of “legislative error,” the Public Prosecution Service (PPS) has said.
The cases involve 17 victims, the majority of whom were children at the time the offences occurred.
The PPS has discovered “a technical change in the law” in 2009 meant the cases should not have been prosecuted in a magistrates court.
It said it is “truly sorry” for the distress the news will cause victims.
The PPS will now consider whether or not to re-run the cases in a crown court.
The cases cover offences of indecent assault or unlawful carnal knowledge which occurred between 1973 and 2009.