Australia's new human rights commissioner has backed the public service's right to sack employees who send inappropriate tweets.
Tim Wilson says their right to freedom of speech is outweighed by their obligation to their employer.
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Michaela Banerji was sacked by the Immigration Department over her posts on Twitter. She argued in court the tweets were covered by an implied constitutional right to freedom of political opinion.
The debate was ignited again this week by the resignation of Australian Taxation Office official Darryl Adams, who said he was still being pursued over a tweet he sent from a parody account two years ago.
Public Service Minister Eric Abetz welcomed the resignation, saying it should be a warning to public servants that they had a responsibility to think before they tweeted.
Mr Wilson backed the minister's stance on Thursday, saying public servants had no constitutional or human right to break their employment conditions.
''Of course people have a right to freedom of speech and freedom of expression, but these people have signed on to employment agreements,'' Mr Wilson said.
''So if [the tweeting] relates to the areas in which they're working in, as some of these cases do, then they really have opted out by accepting the employment questions.
''I don't think there's any ambiguity in some of them, that they shouldn't be engaging in public discussion about matters in which they are directly responsible.''
Mr Wilson, who is outspoken on the topic of free speech, said public servants had the option of quitting their jobs if they were unhappy with the activities of their department.
''They have the choice to seek employment elsewhere if they wish to express those views,'' he said.
Asked if tweets sent under pseudonyms or from parody accounts might be treated more leniently, Mr Wilson said no.
''That's quite irrelevant because they have, in some cases, access to privileged information and they have signed up to those employment conditions,'' he said.
''It doesn't matter, when it comes down to it, because they have signed up to those conditions. It doesn't matter if they then go off and surreptitiously do what they want to do.
''Their right to free speech is not being impinged at all. They have voluntarily signed up to a standard, a code, and if they are in breach of that code, the public service is well within their rights to terminate them.''
Ms Banerji failed in her bid to have the Federal Court force the Immigration Department to reinstate her, and has taken her case to Fair Work Australia after rejecting a settlement offer from the department.
Mr Adams, who could not be contacted on Thursday, was punished in September 2012 for a tweet he sent in January that year describing anti-porn campaigner Melinda Tankard-Reist as ''rootable''.
He was investigated again after the matter was raised last year in Senate estimates and in the media. He was facing new ''sanctions'' when he resigned this month.