Canberra lawyer Mr Collaery and his client, the former spy Witness K, have been charged with breaching federal intelligence laws after Witness K took his concerns about an unlawful Australian bugging operation on Timor-Leste to the Hague.

Mr Collaery intends to fight to clear his name but the case has been limping towards an ACT Supreme Court trial. Its progress has been hobbled by delays and legal skirmishes, including the federal attorney-general's wielding of national security laws to have the case heard in secret and to prevent Mr Collaery choosing his own counsel.

On Monday, Mr Collaery will appeal against court orders granted in the attorney-general's favour to keep much of the case behind closed doors. The government says those orders are necessary to protect Australia's national security interests.

In a joint statement released on Monday, Senator Katy Gallagher and federal MPs Andrew Leigh, Alicia Payne and David Smith - four of the five ACT federal politicians not including senator Zed Seselja - gave the federal opposition's most coherent condemnation of the pair's prosecution yet.

"Canberrans are really concerned about this secret trial of Bernard Collaery and Witness K and they want the government to explain why it's necessary," Ms Payne told The Canberra Times.

She said the public deserved an explanation of why it was in the public interest to press on with the prosecution. In the statement, the group of four said the Morrison government had gone to "absurd" lengths to pursue the pair and that way it had dragged out the case was "unjust".

The united statement follows comments from Labor leader Anthony Albanese last year, who said: "The idea that there should be a prosecution of a whistle-blower, for what's a shameful part of Australia's history, is simply wrong."

Labor has not said what it would do if it was in government, a proposition becoming less of a hypothetical each week as the case drags on and the prospect of an election before the trial becomes more likely. Mr Albanese's words were the strongest hint yet.

However, it remains the subject of speculation because despite shadow attorney-general Mark Dreyfus' repeated attempts to seek government briefings about the prosecution, he and Labor remain as much in the dark about it as the public.

Ms Payne said the government's pursuit of Mr Collaery and Witness K and the moves to conceal matter from public view, spending millions of dollars in the process, were part of a broader shift towards more secrecy and less accountability in government.

The group said with the multiple scandals on Prime Minister Scott Morrison's watch for which he had failed to hold his ministers to account, the "double standards are breathtaking".

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