The immediate trigger for PM&C's intervention was an opinion column in Fairfax newspapers in late May by the business's chairman, Ziggy Switkowski. In this article, published in the middle of the caretaker period, Switkowski justified NBN's decision to ask the Australian Federal Police to investigate alleged leaks of confidential company information to the media and the opposition. The AFP had raided the office of Labor senator Stephen Conroy and the house of a party official in the election campaign's opening week, leading to widespread public criticism of the police and the government. In defence, Switkowski's article attacked the leaks as serving to fuel "political rumourtrage", which he defined as "the circulation of misinformation to diminish an enterprise for political gain". He also vigorously defended the general performance of the national broadband network against partisan criticism.

Opposition finance spokesman Tony Burke complained to PM&C secretary Martin Parkinson about alleged political interference by a public servant during an election campaign. Parkinson, in turn, replied that the article, in his department's view, "was not consistent with the established practices associated with the caretaker conventions". He went on to say that the conventions, as set out in the department's document, Guidance on Caretaker Conventions, do not have any legal force, leaving responsibility for enforcement with the heads of relevant bodies.

Parkinson also revealed that the Communications Department had been shown a draft of Switkowski's article before it was published. After consulting PM&C, the department had indicated to NBN that the conventions applied to it – including its chairman, chief executive and the company as a whole – and that the article would be in breach of them. Parkinson did not indicate what parts of the article were contrary to the conventions, but presumably it was the embargo on official statements that could interpreted as promoting a government policy or attacking the opposition.

Switkowski went ahead and published the article in defiance of PM&C's advice. When the issue became public through the media's publication of Parkinson's reply to Burke, NBN issued a statement saying Switkowski's remarks were consistent with the conventions as they apply to government companies and were justified by the need to restore the trust of staff, which had been severely damaged by false allegations against its management. In the inevitable political barney that followed, Bill Shorten attacked Switkowski for a "shameful breach" of the caretaker conventions, while Malcolm Turnbull backed him (and implicitly contradicted the head of his own department), saying Switkowski had "felt he had to set the facts of the matter straight".

Most media commentary sided with Shorten and Labor, accepting that Switkowski was in clear breach of the conventions as Parkinson had said. However, the issue is not cut and dried. The NBN is not in same position as a normal government department or executive agency. It is one of the few remaining government business enterprises, along with Australia Post, Defence Housing Australia and ASC (formerly the Australian Submarine Corporation). As such, it is a trading company, wholly owned by the government through two shareholders: the minsters of finance and communication. Its management is the responsibility of a board and chief executive, operating at arm's length from shareholding ministers while pursuing objectives set by the government. Its chief officers, including the chairman and chief executive, have a degree of independence not available to heads of government departments or executive agencies.

In recognition of this degree of independence, the caretaker conventions do allow greater discretion for government companies, as the NBN said. The official Guidance on Caretaker Conventions (paragraph 1.6) notes that the conventions were developed primarily in the context of the relationship between, ministers and their departments (and by extension executive agencies). The relationship between ministers and other bodies, such as statutory authorities and government departments, varies. However, these bodies should "observe conventions and practices [emphasis added]".

In its response to Parkinson, the NBN quotes this exemption for government companies' and is clearly relying on it to justify intervention in public debate. For this reason, presumably, it stresses the need to restore staff morale in the face of public criticism, implying that it is a "compelling organisational requirement". We are asked to believe that the NBN is not directly concerned with mistaken criticism of the company as it affects public opinion during an election campaign. What really upsets the NBN management and forced Switkowski to speak out is the demoralising effect of such criticism on their 5000 loyal (and obviously thin-skinned) staff!

The argument stretches credulity and smacks of justification after the event. If restoring staff morale had been the main purpose, why not send a rousing internal message to staff or hold some well-lubricated social get-togethers? Switkowski's article seems clearly designed as a contribution to political debate. To make his case, he was prepared to venture into what Cabinet Secretary Arthur Sinodinos described as a "political minefield".

Switkowski defends the NBN's actions in calling in the AFP to trace the source of leaks and denies the criticisms of the NBN performance that arose from reports of the leaked documents. On using the AFP, Switkowski has a point. The NBN may have appeared heavy-handed in dealing with the leaks, but it was certainly following well-established precedent in using the AFP for this purpose. That the AFP raids took place soon after the election was called was no fault of the NBN and was probably just an unfortunate coincidence on the part of the AFP, which was damned if it did and damned if it didn't.

Switkowski's argument that the leaks were not instances of whistleblowing, as the media claimed, is also strictly speaking correct. Whistleblowing, as normally understood, requires the disclosure of wrongdoing. Disclosing awkward information that management wants to keep confidential does not count as whistleblowing unless actual wrongdoing is involved. Moreover, whistleblowing, as protected under public interest disclosure laws, requires that informants use internal channels before going public.

One can understand NBN managers' desire to get its own version of events on the public record as soon as possible, without waiting until after the end of an unusually long election campaign. Indeed, if Switkowski had wanted to remain within the spirit of the caretaker conventions, he could have crafted a much more low-key response, limited to issues of the AFP and whistleblowing, without engaging in partisan attack. But this would not have met his wish to confront the NBN's political critics, which brought him into direct conflict with the conventions.

Overall, PM&C's judgment, as relayed by its secretary, seems sound. Government companies are certainly cut some slack in applying the conventions, but these are restricted to "legal obligations and compelling organisational requirements". Neither of these exceptions appear intended to allow more outspoken intervention into political debate. The caretaker conventions, it should be remembered, are largely taken up with matters other than public statements. The first four sections of the official guidance document relate to policy decisions, significant appointments, major contracts or undertakings, and international negotiations and visits. These are areas in which government companies may well have legal or "compelling organisational" reasons to take initiatives that cannot await the appointment of new ministers. Public statements are covered in the document's last section on involvement in election activities. Here, there is no suggestion that government companies should be allowed more freedom to engage in political debate.

The NBN's managers, no doubt, may see less reason than most to be politically impartial. They are identified with a highly controversial government policy that they knew would be triumphantly dismantled in the event of a returning Labor government. Switkowski, a Turnbull appointee, could see himself departing, along with other senior managers committed to the Coalition policy. The underlying rationale of the caretaker conventions on public statements is that career public servants should not do or say anything that would damage their capacity to serve an alternative government. It hardly applies to openly politicised office-holders who would not survive a change of government. In this sense, the NBN's defiant breach of the conventions is an exception that proves the rule. It says more about the NBN than about the conventions themselves, which remain firmly in force.

Richard Mulgan is an emeritus professor at the Crawford School of Public Policy at the Australian National University. richard.mulgan@anu.edu.au