A campaign body for victims of rape and sexual violence has said the State must reform its laws in relation to court proceedings for alleged offenders.
The Rape Crisis Network of Ireland (RCNI) said Ireland has one of the highest "attrition" rates in terms of the difference between the number of sexual assaults reported and the number that eventually come to trial.
Kate Mulkerrins, legal co-ordinator of the RCNI, said the Irish judicial system takes the longest time between a person reporting a rape and the case coming to court, and takes double the time of the British system.
Speaking on RTÉ's Morning Ireland, Ms Mulkerrins said that 95 per cent of reported rapes do not make it to court in this State.
Kate Mulkerrins, Rape Crisis Network of Ireland
This was one of the major impediments for those who reported rapes to be encouraged to "stay with it" until trial, she said.
"We are asking people to suspend their lives, often for many years. The average case takes 118 weeks from the time you report until you get before the earliest hearing in court, and that's before there are any adjournments or difficulties in getting a trial on. . . . it is not uncommon to have cases taking three or four years."
She said Ireland had not taken steps towards legislative reform that would require a person's belief that there had been consent to sex to be "reasonable".
"Defendants are, in our system, allowed to assert that whilst their belief wasn't reasonable, they held that belief.
"So we have so much work to do and that work starts the minute somebody reports to the gardaí. We have not enabled people to report to specially trained gardaí throughout the country," she said.
According to the RCNI, a total of 39 people attended the sexual assault treatment unit at Dublin's Rotunda hospital last month - more than one a day.
Ms Mulkerrins said that number was also more than the total number of rape cases to come before the Central Criminal Court for the whole country last year. She said this indicated that the trial process was only dealing with the "tip of the tip of the iceberg".
Labour TD Joanna Tuffy said Ireland's "lamentable" record in prosecuting reported rapes was "worrying in the extreme".
Labour TD Joanna Tuffy
"It is scarcely credible that only one case in 20 actually ends up in court. There is a clear need for significant reform in this area, both in terms of how such cases are investigated and how they are eventually prosecuted," she said.
The Labour Party believed gardaí should receive appropriate training to deal with sexual violence and its investigation, she added.
"The priority should be to tackle the unacceptable delays in hearing cases and to have ready access to the Courts for urgent applications, regardless of where in Ireland the applicant lives," she said.
"We also believe that there should be regular national attitudinal surveys on violence against women to be conducted to inform national strategy in tackling this issue."
The party also called for free legal advice and said a trained sexual assault investigation and liaison officer should be assigned to victims of sexual assault for the duration of their interaction with the criminal justice system.