The mother, who cannot be named for legal reasons, is in the process of having her children returned to her after a five-year legal battle to bring them home.

"I am concerned that Welfare treated me very wrongly and should not have done some of the things that they did," the mother wrote in the letter.

"I am concerned that they may do the same thing to other families and children."

The woman's five children were removed from their home in "emergency action" in 2013. They were separated and put into three different foster homes, including one in NSW. The ACT's highest court ultimately found the decision to remove the children was wrong.

An inquiry into the case was announced on Thursday and was widely welcomed. Those involved in the case believe it will expose systemic issues in the child protection system.

Prominent Canberrans including former chief minister Jon Stanhope had previously called on the government to investigate the details of the case.

Mr Stanhope said he was pleased with the announcement of an inquiry.

He, along with Winnunga Nimmityjah chief executive Julie Tongs and Gugan Gulwan executive director Kim Davison said they would like to see change in how Aboriginal leaders are listened to and respected in their decision making around the removal of Aboriginal children.

"It is very important the inquiry looks specifically at issues around the policies and approach to dealing with Aboriginal and Torres Strait Islander children in contact with the care and protection system, and the arrangements in place in relation to the making of decisions relating to Aboriginal children," Mr Stanhope said.

Ms Tongs said this inquiry had been a long time coming.

"We do have a review happening by Our Booris, Our Way and they're doing an awesome job, but I think we need to take it to the next step, we need to look at what's gone so terribly wrong in child protection."

"This case isn't just a one-off, but it has been the one that has brought the problems to the forefront."

Ms Davison said: "The trauma caused to the mother and her children can and will never be repaired. As a community we need to ensure that our children are thriving in their family environments and that any family who is drawn into the child protection system here in the ACT has the required legal advice and representation. What has happened to this family should never happen again."

Blackburn Chambers barristers Philip Walker SC and James Haddock, who represented the mother in court, said it was terrific that something was going to happen in relation to the case.

"It's a very positive step, but looking at the requirements for anonymity, we are concerned that the provision, if pressed too far, holds within it the potential to defeat the very objective of the inquiry," Mr Haddock said.

Mr Walker said it would be a rare opportunity to cast light on the area.

"We are delighted that the Assembly has responded so quickly to community concern about the ACT child welfare system. Child welfare is a vital area. It is essential that the work of the inquiry made public so it can shed some light on an area which has for too long operated behind closed doors," Mr Walker said.

ACT Law Society family violence and children's committee chair and independent children's representative Lessli Strong welcomed the inquiry, noting the legal system played a huge role in the timeframe of the case after an initial appeal decision was handed down three years after the case was heard.

"Using a particular case to expose systemic issues will be helpful," Ms Strong said.

"What will come out of it on a systemic level will be brilliant, because the way it was conducted legally, I think a number of systemic issues will be illustrated."

The Our Booris, Our Way committee is in the process of reviewing every case of Aboriginal children in care as part of their remit.

Steering committee chair Barbara Causon said there were systemic issues evident in cases reviewed so far. She said their review doesn't get to the "finer details" of an individual case like the inquiry is intended to.

"We're finding issues around both legislation policy and practice issues," Ms Causon said.

"It's not just about how children are removed, its also about how family-finding works and how kinship carers are located and supported and the lack of quality and oversight over cultural care plans."

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