Child protection advocates say there should be a review of laws to ensure Queensland's most dangerous sex offenders remain locked up.
The issue has been brought into sharp focus by the case of serial offender Robert John Fardon, who was briefly released from prison last week.
He's been returned to custody while Attorney-General Jarrod Bleijie mounts a full appeal against an order to set him free under strict supervision.
Bravehearts criminologist Carol Ronken has praised Mr Bleijie for acting in the interests of community safety.
But she says there should be a review of the dangerous sexual offenders act, under which Fardon was sentenced to an indefinite jail term for his crimes against women and girls.
"We call on the government to do a review of the dangerous prisoners act so ... judges are less likely to be able to release these offenders when all the psychiatrists' reports say they should not be released," Ms Ronken told the ABC.
"We are nervous. We have seen, unfortunately, the judges have previously erred on the side of the offender and released them.
Court of Appeal Justice Philip Morrison this week ruled there were arguable grounds to appeal Fardon's release order.
He accepted arguments that the original judge who said Fardon should be freed did not give enough weight to some of the psychiatrists' evidence about him.
That evidence included that Fardon was more likely to reoffend when intoxicated.
At this stage the earliest the appeal can be heard is November 26 or 27.
Fardon has spent most of his adult life in jail for sex offences dating back to 1967.