Ninety-five per cent of rape claims never reach the courts and four out of 10 people who report a rape to gardaí withdraw charges before legal proceedings start.
The Rape Crisis Network in Ireland (RCNI) has commissioned a report to look into the high "attrition rate" of reported rapes.
Kate Mulkerrins, legal co-ordinator of RCNI said Ireland tops the "attrition league table" in a study carried out in 20 European countries. The RCNI felt it was necessary to find out why this was the case and what could be done to address the number of serious sexual assault crimes that fail to reach the courts.
Ireland's ranking "was not a surprise", said Ms Mulkerrins. "The countries that ranked second, third and fourth on the league table were also Commonwealth countries where an adversarial court process exists."
Ms Mulkerrins said the report would focus on three specific aspects of the legal proceedings of reported rape. Firstly, it would include the largest statistical study of complaints made to rape crisis agencies in this country, to assess why the complainants did not make a report to the Garda.
Secondly, researchers would examine court transcripts of trials to find out whether there are specific problems with how rape cases are dealt with, and thirdly, the study would investigate why one-third of files on rape that are submitted to the DPP do not go to trial.
"There is a need for legal reform, because at the moment one of the problems is that there is no statutory definition of consent (to sex)and no analysis of the consent required to be reasonable," Ms Mulkerrins said.
Ellen O'Malley Dunlop, chief executive of the Rape Crisis Centre, said victims of rape were often reluctant to report the crime because they knew the perpetrator. "Ninety-eight per cent of child victims and 64 per cent of adults know their abuser,", she said. "Rape is a difficult thing to talk about and people don't want to put themselves through that."
Ms O'Malley Dunlop and Ms Mulkerrins called for specialist training to be provided to help gardaí to deal with people who report cases of rape. "It is important that gardaí are trained to put together a proper book of evidence because the victim of the crime is usually the only witness,", Ms O'Malley Dunlop said.
Ms Mulkerrins added that many victims of rape feared they would not be believed by the Garda and that victims of rape would be more likely to come forward if there was specialist training for gardaí based in stations around the country. "Germany has invested heavily in specialist training for the police and this has improved the conviction rate of rapists."
The centre runs a confidential, 24-hour helpline on 1800- 77-88-88.