The committee, established by the Senate in April last year, took a leading role in attempting to hold ministers and public servants to account during the pandemic, particularly while normal estimates hearings were suspended during the lockdown. In seeking information, the committee met with regular stone-walling from public servants who refused to answer various questions to which they appeared to have the answers, preferring instead to take the questions on notice. When the committee followed up the requests, the relevant ministers often responded by refusing to answer on the grounds of public interest immunity. The committee was so concerned about the number and nature of these refusals that it decided to devote a whole report to the issue (second interim report, February 2021), unanimously recommending that seven claims of public interest immunity be rejected.

Public interest immunity is originally a common law principle which allows government agencies engaged in litigation to withhold evidence if publication would be against the public interest. The principle balances, on the one hand, the government's legitimate need to keep certain matters confidential and, on the other, the court's interest in making all relevant information available to all parties. The final decision is made by the court on the basis of legal precedents that have established various allowable justifications for immunity, such as national security, safeguarding ongoing legal proceedings and the proper functioning of government.

The principle also applies to Parliament, where the executive has the right to withhold information for a similar range of reasons. Because of the separation of powers, the power to decide lies with Parliament rather than an independent court and is essentially a political rather than a legal judgment. The issue of public interest immunity has been most contentious in the Senate rather than the House of Representatives because of the greater role of Senate committees and the government's regular lack of a Senate majority. The Senate has always refused on principle to defer to legal rulings on immunity (including freedom of information legislation and decisions) but it has developed its own parallel set of practices and guidelines, as set out in a formal Standing Order on Public Interest Immunity Claims adopted in 2009 ("the 2009 order"). The general approach is to accept the executive's right to withhold but within a nuanced, context-dependent assessment that identifies the potential harm to be caused by the particular disclosure. The 2009 order forms the basis for the COVID-19 committee's complaints about the government's abuse of public interest immunity.

The committee's report targets seven questionable applications of public interest immunity by five ministers, covering issues such as COVID-related modelling, the dates the cabinet and national cabinet were first briefed about COVID and about COVID in aged care, and legal advice relating to a privacy amendment bill.

In each case, the ministers had relied on a categorical application of the relevant principle, for example the protection of legal advice to ministers or the confidentiality of cabinet deliberations. They ignored the 2009 order's instruction to specify the harm to the public interest that could result from the disclosure of the particular information or document in that particular case. For example, Senator Michaelia Cash, representing the Minister of Health, in declining to give the date for the Chief Medical Officer's first briefings to cabinet and the national cabinet had simply stated that information about cabinet and its committees could potentially reveal the deliberations of cabinet. She made no attempt to establish that disclosure of this particular information would affect cabinet deliberations or harm the public interest. As the committee commented, "general statements regarding the sanctity of cabinet deliberations do not satisfy the requirements of the 2009 order".

The committee indicated its readiness to explore the option of confidential in-camera disclosure as outlined in the 2009 order. It also offered each of the ministers, should they maintain their claims for immunity, the opportunity of making a 10-minute statement in justification. Overall, the tone of the report, while firm, was also respectful and conciliatory, as confirmed by the willingness of the two Coalition members of the committee to support all recommendations (though they did save face with their parties by appending additional comments about the generally high level of compliance with requests for information).

However, the government remained firmly opposed. In the Senate as whole, government members, including the two Coalition senators who had endorsed the recommendations, voted against, leaving the recommendations to be passed with the support of a non-government majority. Two days later, each of the relevant ministers made brief, single-sentence statements to the Senate reiterating their categorical claims of immunity without justifying argument. The government bluntly imposed its own interpretation, regardless of the more balanced approach of the Senate's own standing order and in defiance of a specific resolution by the Senate. No interest in further discussion. No exploration of possible in camera hearings. The response could not have been more arrogant (giving "the proverbial finger" in the words of Senator Katy Gallagher, the committee chair).

With FOI, high-handed refusals to disclose are at least subject to independent appeal. Claims of public interest immunity, however, remain matters for political decision. All the more reason to expose them to maximum political accountability rather than closing down debate.