Child sex abuse victims who struggle to remember the exact dates they were offended against will be offered greater protection under a new bill set to be introduced to state parliament on Thursday.

Attorney General John Quigley said the Criminal Law Amendment (Uncertain Dates) Bill would attempt to crackdown on predators who have escaped conviction because their victims have been unable to remember exact dates of their offending, due to either age or trauma.

WA attorney General John Quigley. Credit:Heather McNeill

“Unfortunately, there have been cases in Western Australia where perpetrators have evaded conviction as it could not be conclusively established when the offending took place," he said.

"In one case, a teenage accused committed sexual offences against a younger child over many years.