Over the past 1½ decades, there have been four publicised examples of public servants (or similar) losing their jobs for their political expression. I am also aware of several other cases where, for various reasons, expression-related disciplinary action was not contested in court. The four cases that proceeded to litigation are diverse: a customs officer, an army reservist, a Centrelink employee and a public affairs specialist at the Immigration Department. The views expressed cross the political spectrum, from far right to far left.

What unites these four cases – Bennett, Starr, Gaynor and now Banerji – is that each involved criticism of government policy. Which makes the submissions of Western Australia intervening in the High Court in the latest case particularly curious. That state's solicitor-general suggests that the Australian Public Service's code of conduct requires federal public servants to, at all times, "behave in a manner which is 'apolitical'", which limits "the ability" of those employees "to promote or criticise the merits of the policy ideas, principles or commitments of elected representatives, or political parties" (my emphasis).

Western Australia's intervention draws attention to a fact that has often been overlooked in this debate: political neutrality cuts both ways. Perceptions of the public service's impartiality are liable to be undermined in equal measure by overt cheerleading as by robust criticism.

If Michaela Banerji, tweeting under the pseudonym LaLegale, had vigorously complimented the government for its border protection policy, she would still be gainfully employed. If Bernard Gaynor had publicly commended the Australian Defence Force on its cultural change and concomitant embrace of diversity, he would not have lost had his commission in the army reserves.

The utility of these counterfactuals only goes so far. But until the Public Service Commission starts to warn public servants against promoting government policy, they stand as stark examples that – for the current government – neutrality is a one-sided coin. Indeed, the commission's latest guidance, Making public comment on social media: A guide for employees, is instructive. While on one hand the document counsels that "criticising the work, or the administration, of your agency is almost always going to be seen as a breach of the code", several paragraphs later it adds "this doesn't stop you making a positive comment on social media about your agency".

These issues – and the importance of Comcare v Banerji – go far beyond the four decided cases of the past 16 years and the handful of non-litigated examples. The government's actions in high-profile cases produce a chilling effect. As one public servant friend confided after my last column on this topic: "I always err on the side of caution and don't express any political opinions on social media." Whether consciously or otherwise, the actions of all public servants are influenced by cases like Comcare v Banerji and their effect (whether encouraging or deterrent) on the approach of agencies such as the Public Service Commission.

Political neutrality within the public service is an admirable ambition. The deleterious consequences of a partisan bureaucracy are manifold. An apolitical APS is the best bulwark against rife political patronage and a wholesale loss of societal trust in state administration.

But we have not – in the words of former judge Paul Finn – created "a separate caste of public officials ... [nor] relegated our officials to the status of second-class citizens". Public servants don't sign away their political rights on commencement – one cannot contract out of constitutional freedoms. The law in both Australia and the United States has come a long way since American judge Oliver Wendell Holmes jnr quipped in 1892 that a policeman "may have a constitutional right to talk politics, but he has no constitutional right to be a policeman". Achieving the correct balance between necessary impartiality and a public servant's political freedoms is an unenviable task.

But the balance must be struck, both conceptually in legislation and when applied in individual circumstances. And in its statutory and practical explication, the balance should be informed by a nuanced accommodation of the competing principles, not by a government's dislike of criticism from its employees. Public servants – and those who support a robust Australian democracy – can only hope that the High Court is alert to these issues when it sits in Canberra on March 20 to hear Comcare v Banerji.

When the Administrative Appeals Tribunal decided the case that gave rise to the current appeal last April, its two-member panel was sufficiently concerned by the situation to resort to dark literary analogy. Restrictions on anonymous political expression by public servants, AAT deputy president Gary Humphries and member Bernard Hughson wrote, "bear a discomforting resemblance to George Orwell's thoughtcrime".

Australian democracy is a long way from 1984. But that is no reason for complacency. Subject to certain well-defined and clearly outlined restrictions, Australian public servants should be able to engage in political debate – whether by promoting or criticising government policy. There is nothing apolitical about permitting one but not the other.

Kieran Pender is a writer and legal researcher based in London. He is a former research associate with BAL Lawyers in Canberra. kieran.pender@anu.edu.au