The Barr government quickly moved to fix what it described as an "administrative oversight" in the assembly on Thursday.

But for months, correctional centre staff in Canberra ordered people on intensive corrective orders into rehabilitation and to provide samples for drug and alcohol testing without the proper delegation.

Intensive correction orders became a sentencing option in the ACT on March 2, 2016.

The orders allow offenders to serve sentences in the community but under a strict set of restrictions and conditions.

The orders are made by the courts but administered by correctional staff.

But because of an "administrative oversight", correctional centre staff were not delegated the correct authority from the director-general.

As a result, certain directions given to offenders serving an ICO may have been "outside the scope" of correctional staff's authority.

These directions included ordering offenders to provide test samples for drug and alcohol testing, enter rehab or undertake community service work.

The government said the "appropriate delegations" were not in place from March 2 until November 11, 2016.

In a statement, corrections minister Shane Rattenbury said 29 people were sentenced to ICOs during that time.

The amendment will apply retrospectively, limiting the ability of those affected to pursue compensation.

Attorney-General Gordon Ramsay told the assembly on Thursday applying retrospective legislation was a last resort.

"Without the retrospective effect there could be litigation seeking damages over the administration of the scheme," Mr Ramsay said.

"It's important to recognise this is a technical argument only. The fact remains in substance these sentences would have worked exactly as they should have."

But Canberra Liberals spokeswoman Giulia Jones said the bungle had left those in the Justice and Community Safety Directorate "exposed".

She described it as a "monumental stuff-up" and accused Mr Rattenbury of rushing through the amendment to "save face".

"What if those on ICOs forgot to comply with conditions of their orders? 'I forgot' or 'it was an oversight' would not be accepted," Mrs Jones said.

Mrs Jones said according to the amended bill, close to 200 staff have been administering ICOs without the correct authority to do so.

She said she was concerned about the financial implications for the ACT if those affected decided to take action against the government or corrective staff.

She said it called into question the validity of the orders and the samples taken without authority.

However Mr Rattenbury said the sentences imposed by the courts were lawful.

"The decisions were taken in good faith, whether delegations in place or not. Officers acted as they should have under the legislation, and on that basis what we're doing here is ensuring clarity of that and avoiding the risk for excessive litigation if the matter is brought up," Mr Rattenbury said.

"It's an unfortunate oversight, it's a little bit embarrassing but the purpose of the legislation today is to fix that up and get on with the business we need to focus on, which is working with our detainees to get their lives back on track.

ACT Bar Association president Ken Archer criticised the government and the justice directorate for failing to notify the legal profession.

"If the issue was discovered some time ago, why wasn't this revealed to people coming before the Sentence Administration Board who may have been affected and why wasn't the profession notified of this problem so appropriate action could be taken on behalf of those who were affected?" Mr Archer said.

"It's an unusual circumstance for the directorate not to have notified the profession of legislation of this type. I've not known this to have occurred before, it may have just been an oversight on this occasion but Im' concerned there may have been a desire to head off possible claims that may have arisen as a result of people being sent to jail, possibly illegally."

ACT Law Society president Sarah Avery said the society did not accept government's argument that the amendments were simply a technical or administrative fix.

"The retrospective operation of the legislation means that such people, having been detained, apparently have no redress," Ms Avery said.

"The apparently secretive way in which this matter has been handled adds to the Society's existing concerns regarding the operation of ICOs."