Another day, another attack on the ability of public servants to participate in Australian democracy.

On Monday the Australian Public Service Commission (APSC) released revised guidance on how federal government employees should use social media. It advised that expressing disagreement with government policy, criticising the prime minister or even liking a negative social media post could land public servants in hot water. This, the APSC contended, was the case whether or not comments were made anonymously, on a private account or after hours.

The new guidelines, which public service commissioner John Lloyd insists are “not more restrictive than previous guidance”, represent the latest frontier in a sustained campaign of government encroachment on the free speech of public servants. In 2013, an immigration officer was fired for criticising department policy on Twitter using a pseudonym. Last year, Centrelink was forced to reinstate an employee who had been terminated for speaking out online. In the Australian Capital Territory meanwhile, the local Labor government recently attempted to restrict criticism from public servants and force them to “dob in” colleagues who disobeyed. For every case that makes the headlines, there are also many more where public servants are sanctioned behind closed doors.

This debate is not novel. In 1902, the newly-established federal government instituted regulations that forbade public servants from publicly discussing or “in any way” promoting political movements. Astonishingly, a version of this blanket prohibition remained law until 1974, when it was repealed “to give public servants greater freedom”.

Nor is the issue straightforward. The government undoubtedly has a legitimate interest in maintaining a neutral and effective bureaucracy. The overt politicisation of the public service would have hugely deleterious consequences, from wholesale turnover following change of government to diminished societal trust in public administration.

But that does not mean public servants should be silenced. Doing so not only disenfranchises them from proper participation in the system of Australian democracy; Australia’s limited free speech protections, it should be remembered, are predicated on the nexus between political communication and representative government. But it also deprives the broader community of important voices in political debate – public servants are often some of the most qualified contributors to policy discussion.

The APSC’s guidance is blind to such countervailing considerations. It offers: “Criticising the work, or the administration, of your agency is almost always going to be seen as a breach of the [code of conduct].” Praise is welcome, though. “This doesn’t stop you making a positive comment on social media about your agency,” the guidelines continue, making a mockery of the stated desire for impartiality. Neutrality, it seems, does not swing both ways.

The latest diktats from commissioner Lloyd’s office also raise intriguing legal questions. In 2013, amendments to the public service act sought to extend the code of conduct’s reach – certain obligations were professed to apply “at all times.” Monday’s guidance argued: “[A public servant’s] capacity to affect the reputation of [their] agency and the APS does not stop when [they] leave the office … APS employees are required by law to uphold the APS Values at all times.”

Except, “at all times” may not really mean “at all times”. In 2016, Fair Work Commission vice-president Adam Hatcher dismissed arguments to that effect from Centrelink. “I reject completely,” he wrote, the proposition that the law requires public servants “to be ‘respectful’ at all times outside of working hours, including in the expression of their attitude to the government of the day.” Such a “gross intrusion into the non-working lives and rights of public servants”, Hatcher suggested, “would require express and absolutely unambiguous language.”

The APSC sought to buttress the constitutionality of its guidance by reference to Australia’s weak free speech protections: “The implied Constitutional freedom of political communication is not a protection of free speech for individuals.” It continued: “None of the litigation brought before various courts has successfully argued that the Public Service Act, or the Code of Conduct, amounts to an undue limitation of the freedom of political communication.”

Except, this is a half-truth at best. In 2003, customs officer Peter Bennett was directed not to make media comment in his capacity as a union representative where doing so would disclose information gained via his official position. Bennett refused to comply and was charged with breaching a secrecy regulation made under the public service act’s predecessor. Justice Paul Finn of the federal court invalidated the regulation on free speech grounds.

It is a great shame the APSC overlooked this case while preparing new social media guidance for the public service. If its drafters had read the judgment carefully, they might have reflected on one particular line. “Public servants cannot be,” Finn quoted, “‘silent members of society’”.

Disclosure: John Wilson acted for Peter Bennett in the federal court proceedings.