The 28-year-old man was jailed for sexual crimes against early- to mid-adolescent boys, with psychiatrists arguing he was at risk of committing a serious sexual offence if he did not complete a sexual offenders program before being released.

Despite being in custody since June 2017 he was not approached to undertake a sexual offender treatment program.

The Supreme Court ruled the man would remain in detention, so he could take part in a "getting started" program in January 2019, and a high-intensity sexual offenders program, which runs for 39 weeks, from April.

Previously, it was anticipated the next vacancy for the program would be in November 2019.

Justice Peter Applegarth said if the system had offered the man a place in a high-intensity sexual offenders program over the past 18 months, and he had completed the program satisfactorily, he probably would have been released from prison in late 2018 on a supervision order.

"The system having failed the respondent and the community in this way, regrettably he must be detained in custody for treatment," he said.

Justice Applegarth said it was "completely unsatisfactory" the man was not offered a place in the high-intensity sexual offenders program long ago and he must now be detained for treatment he should have received during his term of imprisonment.

Queensland Council for Civil Liberties vice-president Terry O'Gorman said the criticism like the "system [has] failed" were strong words coming from a Supreme Court judge.

"The problems caused by Corrective Services' failure to devote sufficient money to prisoner rehabilitation programs for sexual offenders are not restricted to this case," he said.

"As a criminal defence lawyer, I can say the problem is widespread.

"Sexual offenders liable to come under the dangerous prisoner regime frequently are not offered rehabilitation programs until close to their full time sentence, often causing them to be kept in prison long beyond their proper release date."

Mr O'Gorman has written to Corrective Services Minister Mark Ryan calling for a review of rehabilitation programs in prisons.

A spokesman for Mr Ryan said the prisoner in question was being given priority access to the required programs.

He said the provision of rehabilitation services was continually under review by Queensland Corrective Services.

"Whilst the demand for the various sexual offending programs cannot be perfectly predicted, QCS works to ensure all prisoners have the opportunity to complete their required program prior to their parole eligibility date and/or custodial end date wherever possible," the spokesman said.

The spokesman said sexual offender programs were not available for prisoners on remand, so as to not interfere with the court process, and the only time they could be delivered was following sentence.

In 2017-18, QCS allocated $44.7 million for rehabilitation programs in prisons and community settings.