Almost four out of 10 rape and sex offence cases brought before the criminal courts last year did not secure a conviction, figures show.
A total of 83 suspected sex offenders were charged in 2012 - a 32% jump in two years - with 21 acquitted and 12 nolle prosequi entered.
The Court Service said domestic violence cases also soared by 20% as new laws allowed same-sex couples, co-habiting partners and former couples with a child to apply for protection.
Some 12,655 men and women sought a safety, protection or barring order, with 230 people jailed or handed suspended sentences for breaching the orders.
Elsewhere 41 murder cases were heard in the Central Criminal Court, with 35 convictions for murder, manslaughter or attempted murder.
But the Court service said there was a significant decrease in high visibility, high nuisance and highly dangerous activity, including a record 41% fall in drink-driving cases over two years.
Almost 160,000 defendants accused of 384,231 offences came before the courts, resulting in 693 criminal trials.
Justice Minister Alan Shatter said the drop in numbers before the court, and falls recorded in recent crime figures, was down to smart policing initiatives despite having a smaller force.
"This is now a safer country than it was two and a half years ago," he said.
Garda Commissioner Martin Callinan said fighting crime remains a constant battle for gardai and warned the theft of mobile phones and cash remains a concern, particularly in city centres.