A legal expert will be appointed to lead the inquiry into Bruce Lehrmann's case and settle on the terms of reference in January, before providing findings to the ACT government in the first half of 2023.

Chief Minister Andrew Barr announced on Wednesday a board of inquiry would be established to consider the handling of the case, following a series of explosive complaints that have "deeply concerned" the ACT government.

"An independent review of the roles played by the criminal justice agencies involved is the most appropriate response," Mr Barr said.

The board of inquiry - which will be able to hold public and private hearings, issue search warrants and compel witnesses to appear - will also consider whether support provided by ACT Victims of Crime Commissioner Heidi Yates to alleged sexual assault victim Brittany Higgins was appropriate.

Ms Yates, who declined to comment on Wednesday, accompanied Ms Higgins to a police interview in 2021, and was by her side throughout the ACT Supreme Court rape trial of Lehrmann, 27, in October.

The trial was aborted because of juror misconduct, which will be another focus for the inquiry as it considers the options available for addressing such occurrences in the territory.

But the inquiry is set to primarily probe the engagement between the ACT Director of Public Prosecutions and ACT Policing about the prospect of charges being laid, the call to proceed to trial and the decision not to hold a retrial after the case collapsed.

The conduct of police and the territory's top prosecutor will be squarely in focus after the latter accused investigators of pressuring him not to run the case and "bullying" Ms Higgins.

"The board of inquiry will consider whether the functions of the various criminal justice entities involved in the matter were discharged with appropriate rigour, impartiality, and independence," the government said.

Attorney-General Shane Rattenbury said ACT Policing, the Director of Public Prosecutions and the Victims of Crime Commissioner had all indicated they would cooperate with the inquiry.

Mr Rattenbury stressed that the inquiry was not about revisiting the trial, its evidence or outcome.

"It is expected that the inquiry will have regard to investigations which other bodies may be conducting regarding these matters," he said.

"I would ask everyone to respect the privacy of individuals who will be involved in this inquiry."

The Attorney-General said he was "deeply concerned by the allegations" made since the trial's collapse.

"The ACT government is absolutely mindful of the need for public confidence in the criminal justice system here in the territory," he said.

"Recent public reporting and commentary in relation to the case ... raises issues that may have wider implications for the prosecution of criminal matters here in the territory."

Mr Lehrmann denies raping Ms Higgins at Parliament House when the pair were federal Liberal Party staffers in March 2019.

The rape charge levelled at him was dropped earlier this month because of concerns about the impact of the case on Ms Higgins' mental health.

His barrister, Steven Whybrow SC, issued a short statement after the inquiry was announced.

"Mr Lehrmann welcomes an inquiry and hopes the terms of reference will extend to an examination of all aspects of this matter, including decisions not to prosecute various individuals and the efforts taken by the DPP to ensure a fair trial," Mr Whybrow said.

Ms Higgins also reacted to the news, posting a screenshot of a headline about the inquiry on Instagram with the caption "sunlight is the best disinfectant".

The newly announced inquiry will complement the Australian Commission for Law Enforcement Integrity investigation launched in response to the Director of Public Prosecutions' complaints about police.

The government spent more than a week finalising the detail and structure of its probe, resolving the issue posed by ACT Policing, an arm of the Australian Federal Police, falling outside the scope of the ACT Integrity Commission.

Calls for a public inquiry had been growing since the release of an explosive letter Director of Public Prosecutions Shane Drumgold SC sent ACT chief police officer Neil Gaughan about the case.

In his November 1 letter, released under freedom of information laws, Mr Drumgold complained to Deputy Commissioner Gaughan about being pressured by police not to prosecute Mr Lehrmann.

He accused investigators of aligning themselves with Mr Lehrmann's defence when he did not agree with their position, and of leaving Ms Higgins feeling as though police were "bullying" her to withdraw her sexual assault complaint.

Deputy Commissioner Gaughan emailed his staff after the letter was released to stress that Mr Drumgold's allegations against individual ACT Policing members were "untested".

Mr Drumgold's letter outlined his view that there should be "a public inquiry into both political and police conduct in this matter".

The chief police officer indicated in his message to officers he would welcome a broader public inquiry, which would also examine issues including the conduct of prosecutors.

On Wednesday, an ACT Policing spokesman acknowledged the government's announcement and told The Canberra Times the force "looks forward to engaging with the inquiry in the coming months".

ACT Opposition Leader Elizabeth Lee and Australian Federal Police Association president Alex Caruana had been among those urging the government to establish a public inquiry.

Ms Lee welcomed Wednesday's announcement, but she said she was concerned the government seemed to have outlined an "exhaustive" list of matters that would be examined.

"We know that there have been serious and various concerns, raised by the police force, the legal profession and the broader public, about what has happened in this case," the Canberra Liberals leader said.

"I note, for example, and it is concerning that the ACT government's press release talked about several issues but did not mention the very, very serious allegation of political interference that has been raised, and that is something that I will be looking to ensure is contained in the terms of reference when they are released."

Ms Lee specifically raised concerns about Mr Rattenbury, the ACT Greens leader, looking to rush through amendments to the Evidence Act ahead of Mr Lehrmann's retrial, prior to the case being discontinued.

Asked whether his actions could also be examined as part of the inquiry, Mr Rattenbury said that would be open to the person conducting it.

Mr Caruana joined Ms Lee in welcoming the inquiry's announcement, saying "any potential influence exerted" by Mr Rattenbury or his office on the case "must be scrutinised".

He added that Mr Drumgold's public commentary about the matter required attention.

"The inquiry should examine whether Mr Drumgold's explosive public statements were befitting of the ACT's top prosecutor," the police union boss said on Wednesday.

"The national media frenzy caused by these claims have eroded the community's faith in its institutions.

"Several other, more suitable mechanisms were available for Mr Drumgold to air his grievances."

Mr Drumgold told The Canberra Times he welcomed the establishment of a board of inquiry.

"Notwithstanding the independence of both institutions, the DPP and ACT Policing relationships remains strong and collegiate, and the joint support for this inquiry speaks to this strength and collegiality," he said.